Day 10

.gitignore

@@ -0,0 +1,2 @@
+*/**
+!*/*.cpp

Day1/part1.cpp

@@ -0,0 +1,25 @@
+#include <iostream>
+#include <string>
+
+int main(int argc, char* argv[])
+{
+    std::string line;
+    int total = 0;
+    int max = 0;
+    while(std::getline(std::cin, line))
+    {
+        if (0 == line.size())
+        {
+            if (total > max)
+            {
+                max = total;
+            }
+            total = 0;   
+        }
+        else
+        {
+            total += stoi(line);
+        }
+    }
+    std::cout << max << std::endl;
+}

Day1/part2.cpp

@@ -0,0 +1,26 @@
+#include <iostream>
+#include <string>
+#include <vector>
+#include <algorithm>
+
+int main(int argc, char* argv[])
+{
+    std::string line;
+    int total = 0;
+    std::vector<int> sums;
+    while(std::getline(std::cin, line))
+    {
+        if (0 == line.size())
+        {
+            sums.push_back(total);
+            total = 0;   
+        }
+        else
+        {
+            total += stoi(line);
+        }
+    }
+
+    std::sort(sums.begin(), sums.end(), std::greater<>());
+    std::cout << sums[0] + sums[1] + sums[2] << std::endl;
+}

Day10/part1.cpp

@@ -0,0 +1,33 @@
+#include <iostream>
+#include <string>
+
+using namespace std;
+
+int main(int argc, char* argv[])
+{
+    string line;
+    int cycle = 1;
+    int accumulator = 1;
+    int answer = 0;
+    while(getline(cin, line))
+    {
+        int next_adden = 0;
+        if (line.substr(0,4).compare("addx") == 0)
+        {
+            next_adden = stoi(line.substr(5));
+            cycle++;
+            if ((cycle-20)%40 == 0)
+            {
+                answer += cycle*accumulator;
+            }
+            accumulator += next_adden;
+        }
+
+        cycle++;
+        if ((cycle-20)%40 == 0)
+        {
+            answer += cycle*accumulator;
+        }
+    }
+    cout << answer << endl;
+}

Day10/part2.cpp

@@ -0,0 +1,50 @@
+#include <iostream>
+#include <string>
+
+using namespace std;
+
+int main(int argc, char* argv[])
+{
+    string line;
+    int cycle = 1;
+    int x = 0;
+    int accumulator = 1;
+    while(getline(cin, line))
+    {
+        if (accumulator >= x-1 && accumulator <= x+1)
+        {
+            cout << "#";
+        }
+        else
+        {
+            cout << " ";
+        }
+        cycle++;
+        x++;
+        if (0 == x%40)
+        {
+            x = 0;
+            cout << endl;
+        }
+
+        if (line.substr(0,4).compare("addx") == 0)
+        {            
+            if (accumulator >= x-1 && accumulator <= x+1)
+            {
+                cout << "#";
+            }
+            else
+            {
+                cout << " ";
+            }
+            accumulator += stoi(line.substr(5));
+            cycle++;
+            x++;
+            if (0 == x%40)
+            {
+                x = 0;
+                cout << endl;
+            }
+        }
+    }
+}

Day2/part1.cpp

@@ -0,0 +1,20 @@
+#include <iostream>
+#include <string>
+#include <algorithm>
+
+using namespace std;
+
+string plays[] = {"A X", "A Y", "A Z", "B X", "B Y", "B Z", "C X", "C Y", "C Z"};
+int play_scores[] = {1 + 3, 2 + 6, 3 + 0, 1 + 0, 2 + 3, 3 + 6, 1 + 6, 2 + 0, 3 + 3};
+
+int main(int argc, char* argv[])
+{
+    int total_score = 0;
+    string line;
+    while(getline(cin, line))
+    {
+        int i = find(&plays[0], &plays[9], line)-&plays[0];
+        total_score += play_scores[i];
+    }
+    cout << total_score << endl;
+}

Day2/part2.cpp

@@ -0,0 +1,20 @@
+#include <iostream>
+#include <string>
+#include <algorithm>
+
+using namespace std;
+
+string plays[] = {"A X", "A Y", "A Z", "B X", "B Y", "B Z", "C X", "C Y", "C Z"};
+int play_scores[] = {3 + 0, 1 + 3, 2 + 6, 1 + 0, 2 + 3, 3 + 6, 2 + 0, 3 + 3, 1 + 6};
+
+int main(int argc, char* argv[])
+{
+    int total_score = 0;
+    string line;
+    while(getline(cin, line))
+    {
+        int i = find(&plays[0], &plays[9], line)-&plays[0];
+        total_score += play_scores[i];
+    }
+    cout << total_score << endl;
+}

Day3/part1.cpp

@@ -0,0 +1,36 @@
+#include <iostream>
+#include <string>
+#include <algorithm>
+
+using namespace std;
+
+int main(int argc, char* argv[])
+{
+    int total = 0;
+
+    string line;
+    while(getline(cin, line))
+    {
+        string half1 = line.substr(0, line.size()/2);
+        string half2 = line.substr(line.size()/2);
+
+        sort(half1.begin(), half1.end());
+        sort(half2.begin(), half2.end());
+
+        string remaining;
+        set_intersection(half1.begin(), half1.end(), half2.begin(), half2.end(), back_inserter(remaining));
+
+        int value;
+        if (remaining[0] >= 'a')
+        {
+            value = remaining[0]-'a'+1;
+        }
+        else
+        {
+            value = remaining[0]-'A'+27;
+        }
+        
+        total += value;
+    }
+    cout << total << endl;
+}

Day3/part2.cpp

@@ -0,0 +1,38 @@
+#include <iostream>
+#include <string>
+#include <algorithm>
+
+using namespace std;
+
+int main(int argc, char* argv[])
+{
+    int total = 0;
+
+    string line1,line2,line3;
+    while(getline(cin, line1))
+    {
+        getline(cin, line2);
+        getline(cin, line3);
+
+        sort(line1.begin(), line1.end());
+        sort(line2.begin(), line2.end());
+        sort(line3.begin(), line3.end());
+
+        string first_intersection, second_intersection;
+        set_intersection(line1.begin(), line1.end(), line2.begin(), line2.end(), back_inserter(first_intersection));
+        set_intersection(first_intersection.begin(), first_intersection.end(), line3.begin(), line3.end(), back_inserter(second_intersection));
+
+        int value;
+        if (second_intersection[0] >= 'a')
+        {
+            value = second_intersection[0]-'a'+1;
+        }
+        else
+        {
+            value = second_intersection[0]-'A'+27;
+        }
+        
+        total += value;
+    }
+    cout << total << endl;
+}

Day4/part1.cpp

@@ -0,0 +1,33 @@
+#include <iostream>
+#include <string>
+#include <algorithm>
+
+using namespace std;
+
+int main(int argc, char* argv[])
+{
+    int total = 0;
+
+    string line;
+    while(getline(cin, line))
+    {
+        string::size_type n = line.find(',');
+        string half1 = line.substr(0,n);
+        string half2 = line.substr(n+1);
+
+        n = half1.find('-');
+        int half1_start = stoi(half1.substr(0,n));
+        int half1_end = stoi(half1.substr(n+1));
+
+        n = half2.find('-');
+        int half2_start = stoi(half2.substr(0,n));
+        int half2_end = stoi(half2.substr(n+1));
+
+        if ((half1_start <= half2_start && half1_end >= half2_end) ||
+            (half2_start <= half1_start && half2_end >= half1_end))
+        {
+            total++;            
+        }
+    }
+    cout << total << endl;
+}

Day4/part2.cpp

@@ -0,0 +1,32 @@
+#include <iostream>
+#include <string>
+#include <algorithm>
+
+using namespace std;
+
+int main(int argc, char* argv[])
+{
+    int total = 0;
+
+    string line;
+    while(getline(cin, line))
+    {
+        string::size_type n = line.find(',');
+        string half1 = line.substr(0,n);
+        string half2 = line.substr(n+1);
+
+        n = half1.find('-');
+        int half1_start = stoi(half1.substr(0,n));
+        int half1_end = stoi(half1.substr(n+1));
+
+        n = half2.find('-');
+        int half2_start = stoi(half2.substr(0,n));
+        int half2_end = stoi(half2.substr(n+1));
+
+        if (!(half1_end < half2_start || half2_end < half1_start))
+        {
+            total++;            
+        }
+    }
+    cout << total << endl;
+}

Day5/part1.cpp

@@ -0,0 +1,91 @@
+#include <iostream>
+#include <string>
+#include <unordered_map>
+#include <vector>
+#include <algorithm>
+
+using namespace std;
+
+int main(int argc, char* argv[])
+{
+    bool instruction_mode = false;
+    string line;
+    unordered_map<int, string> stacks;
+
+    struct Instruction
+    {
+        int quantity;
+        int from;
+        int to;
+    };
+
+    vector<Instruction> instructions;
+
+    int stack_max = 0;
+
+    while (getline(cin, line))
+    {
+        if (0 == line.size())
+        {
+            instruction_mode = true;
+
+            for (auto &it : stacks)
+            {
+                it.second = it.second.substr(0, it.second.size()-1);
+            }
+
+            continue;
+        }
+
+        if (instruction_mode)
+        {
+            Instruction instruction;
+            line = line.substr(5);
+            string::size_type n = line.find(' ');
+            instruction.quantity = stoi(line.substr(0,n));
+            line = line.substr(n+6);
+            n = line.find(' ');
+            instruction.from = stoi(line.substr(0,n));
+            line = line.substr(n+4);
+            instruction.to = stoi(line);
+
+            instructions.push_back(instruction);
+        }
+        else
+        {
+            for (int i = 1, s = 1; i < line.size(); i+=4, s++)
+            {
+                if (line[i] == ' ')
+                {
+                    continue;
+                }
+
+                if (!stacks.contains(s))
+                {
+                    stacks[s] = "";
+                }
+
+                stacks[s] += line[i];
+
+                if (s > stack_max)
+                {
+                    stack_max = s;
+                }
+            }
+        }
+    }
+
+    for (unsigned int i = 0; i < instructions.size(); i++)
+    {
+        string taken = stacks[instructions[i].from].substr(0, instructions[i].quantity);
+        reverse(taken.begin(), taken.end());
+        stacks[instructions[i].from] = stacks[instructions[i].from].substr(instructions[i].quantity);
+        stacks[instructions[i].to] = taken + stacks[instructions[i].to];
+    }
+
+    for(int s = 1; s <= stack_max; s++)
+    {
+        cout << stacks[s][0];
+    }
+    cout << endl;
+}

Day5/part2.cpp

@@ -0,0 +1,90 @@
+#include <iostream>
+#include <string>
+#include <unordered_map>
+#include <vector>
+#include <algorithm>
+
+using namespace std;
+
+int main(int argc, char* argv[])
+{
+    bool instruction_mode = false;
+    string line;
+    unordered_map<int, string> stacks;
+
+    struct Instruction
+    {
+        int quantity;
+        int from;
+        int to;
+    };
+
+    vector<Instruction> instructions;
+
+    int stack_max = 0;
+
+    while (getline(cin, line))
+    {
+        if (0 == line.size())
+        {
+            instruction_mode = true;
+
+            for (auto &it : stacks)
+            {
+                it.second = it.second.substr(0, it.second.size()-1);
+            }
+
+            continue;
+        }
+
+        if (instruction_mode)
+        {
+            Instruction instruction;
+            line = line.substr(5);
+            string::size_type n = line.find(' ');
+            instruction.quantity = stoi(line.substr(0,n));
+            line = line.substr(n+6);
+            n = line.find(' ');
+            instruction.from = stoi(line.substr(0,n));
+            line = line.substr(n+4);
+            instruction.to = stoi(line);
+
+            instructions.push_back(instruction);
+        }
+        else
+        {
+            for (int i = 1, s = 1; i < line.size(); i+=4, s++)
+            {
+                if (line[i] == ' ')
+                {
+                    continue;
+                }
+
+                if (!stacks.contains(s))
+                {
+                    stacks[s] = "";
+                }
+
+                stacks[s] += line[i];
+
+                if (s > stack_max)
+                {
+                    stack_max = s;
+                }
+            }
+        }
+    }
+
+    for (unsigned int i = 0; i < instructions.size(); i++)
+    {
+        string taken = stacks[instructions[i].from].substr(0, instructions[i].quantity);
+        stacks[instructions[i].from] = stacks[instructions[i].from].substr(instructions[i].quantity);
+        stacks[instructions[i].to] = taken + stacks[instructions[i].to];
+    }
+
+    for(int s = 1; s <= stack_max; s++)
+    {
+        cout << stacks[s][0];
+    }
+    cout << endl;
+}

Day6/part1.cpp

@@ -0,0 +1,22 @@
+#include <iostream>
+#include <string>
+#include <algorithm>
+
+using namespace std;
+
+int main(int argc, char* argv[])
+{
+    string signal;
+    cin >> signal;
+
+    for (int i = 0; i < signal.size()-4; i++)
+    {
+        string segment = signal.substr(i,4);
+        sort(segment.begin(), segment.end());
+        if (segment.end() == std::unique(segment.begin(), segment.end()))
+        {
+            cout << i+4 << endl;
+            break;
+        }
+    }
+}

Day6/part2.cpp

@@ -0,0 +1,22 @@
+#include <iostream>
+#include <string>
+#include <algorithm>
+
+using namespace std;
+
+int main(int argc, char* argv[])
+{
+    string signal;
+    cin >> signal;
+
+    for (int i = 0; i < signal.size()-14; i++)
+    {
+        string segment = signal.substr(i,14);
+        sort(segment.begin(), segment.end());
+        if (segment.end() == std::unique(segment.begin(), segment.end()))
+        {
+            cout << i+14 << endl;
+            break;
+        }
+    }
+}

Day7/part1.cpp

@@ -0,0 +1,119 @@
+#include <iostream>
+#include <string>
+#include <algorithm>
+#include <vector>
+#include <unordered_map>
+
+using namespace std;
+
+struct Dir
+{
+    Dir(string name) : name{name},subdir{vector<Dir>()},files{unordered_map<string,int>()},parent{nullptr} {}
+
+    string name;
+    vector<Dir> subdir;
+    unordered_map<string, int> files;
+    Dir* parent;
+};
+
+int get_sum_small_dirs(Dir dir);
+
+int get_dir_size(Dir dir);
+
+int main(int argc, char* argv[])
+{
+    Dir root_dir("/");
+
+    Dir* current_dir = &root_dir;
+
+    string line;
+    getline(cin, line);
+    getline(cin, line);
+    while (line.size() != 0)
+    {
+        if (line.substr(2,2).compare("cd") == 0)
+        {
+            if (line.substr(5).compare("..") == 0)
+            {
+                current_dir = current_dir->parent;
+            }
+            else
+            {
+                for (vector<Dir>::iterator it = current_dir->subdir.begin(); it != current_dir->subdir.end(); ++it)
+                {
+                    if (it->name.compare(line.substr(5)) == 0)
+                    {
+                        current_dir = &(*it);
+                        break;
+                    }
+                }
+            }
+
+            getline(cin, line);
+            continue;
+        }
+        else if (line.substr(2,2).compare("ls") == 0)
+        {
+            while(true)
+            {
+                getline(cin, line);
+
+                if (line.size() == 0 || line[0] == '$')
+                {
+                    break;
+                }
+
+                if (line.substr(0,3).compare("dir") == 0)
+                {
+                    Dir subdir(line.substr(4));
+                    subdir.parent = current_dir;
+                    current_dir->subdir.push_back(subdir);
+                }
+                else
+                {
+                    string::size_type n = line.find(' ');
+                    int file_size = stoi(line.substr(0,n));
+                    string file_name = line.substr(n+1);
+                    current_dir->files[file_name] = file_size;
+                }
+            }
+        }
+    }
+
+    cout << get_sum_small_dirs(root_dir) << endl;
+}
+
+int get_sum_small_dirs(Dir dir)
+{
+    int total_size = 0;     
+
+    int dir_size = get_dir_size(dir);
+
+    if (dir_size < 100000)
+    {
+        total_size += dir_size;
+    }
+
+    for(unsigned int i = 0; i < dir.subdir.size(); i++)
+    {
+        total_size += get_sum_small_dirs(dir.subdir[i]);
+    }
+
+    return total_size;
+}
+
+int get_dir_size(Dir dir)
+{
+    int size = 0;
+    for(auto &file_it : dir.files)
+    {
+        size += file_it.second;
+    }
+
+    for(unsigned int i = 0; i < dir.subdir.size(); i++)
+    {
+        size += get_dir_size(dir.subdir[i]);
+    }
+
+    return size;
+}

Day7/part2.cpp

@@ -0,0 +1,112 @@
+#include <iostream>
+#include <string>
+#include <algorithm>
+#include <vector>
+#include <unordered_map>
+
+using namespace std;
+
+struct Dir
+{
+    Dir(string name) : name{name},subdir{vector<Dir>()},files{unordered_map<string,int>()},parent{nullptr} {}
+
+    string name;
+    vector<Dir> subdir;
+    unordered_map<string, int> files;
+    Dir* parent;
+};
+
+vector<int> dir_sizes;
+
+int get_dir_size(Dir dir);
+
+int main(int argc, char* argv[])
+{
+    Dir root_dir("/");
+
+    Dir* current_dir = &root_dir;
+
+    string line;
+    getline(cin, line);
+    getline(cin, line);
+    while (line.size() != 0)
+    {
+        if (line.substr(2,2).compare("cd") == 0)
+        {
+            if (line.substr(5).compare("..") == 0)
+            {
+                current_dir = current_dir->parent;
+            }
+            else
+            {
+                for (vector<Dir>::iterator it = current_dir->subdir.begin(); it != current_dir->subdir.end(); ++it)
+                {
+                    if (it->name.compare(line.substr(5)) == 0)
+                    {
+                        current_dir = &(*it);
+                        break;
+                    }
+                }
+            }
+
+            getline(cin, line);
+            continue;
+        }
+        else if (line.substr(2,2).compare("ls") == 0)
+        {
+            while(true)
+            {
+                getline(cin, line);
+
+                if (line.size() == 0 || line[0] == '$')
+                {
+                    break;
+                }
+
+                if (line.substr(0,3).compare("dir") == 0)
+                {
+                    Dir subdir(line.substr(4));
+                    subdir.parent = current_dir;
+                    current_dir->subdir.push_back(subdir);
+                }
+                else
+                {
+                    string::size_type n = line.find(' ');
+                    int file_size = stoi(line.substr(0,n));
+                    string file_name = line.substr(n+1);
+                    current_dir->files[file_name] = file_size;
+                }
+            }
+        }
+    }
+
+    int space_needed = 30000000 - 70000000 + get_dir_size(root_dir);
+
+    sort(dir_sizes.begin(), dir_sizes.end());
+
+    for(unsigned int i = 0; i < dir_sizes.size(); i++)
+    {
+        if (dir_sizes[i] >= space_needed)
+        {
+            cout << dir_sizes[i] << endl;
+            break;
+        }
+    }
+}
+
+int get_dir_size(Dir dir)
+{
+    int size = 0;
+    for(auto &file_it : dir.files)
+    {
+        size += file_it.second;
+    }
+
+    for(unsigned int i = 0; i < dir.subdir.size(); i++)
+    {
+        size += get_dir_size(dir.subdir[i]);
+    }
+
+    dir_sizes.push_back(size);
+    return size;
+}

Day8/part1.cpp

@@ -0,0 +1,93 @@
+#include <iostream>
+#include <string>
+
+using namespace std;
+
+int main(int argc, char* argv[])
+{
+    string line;
+    getline(cin, line);
+
+    int length = line.size();
+
+    int* forest = new int[length*length];
+    int in_y = 0;
+    do
+    {
+        for(int i = 0; i < length; i++)
+        {
+            forest[i+in_y*length] = line[i]-'0';
+        }
+        ++in_y;
+    } while(getline(cin, line));
+
+    bool* visible = new bool[length*length];
+    for(int i = 0; i < length*length; i++)
+    {
+        visible[i] = false;
+    }
+
+    for(int x = 0; x < length; x++)
+    {
+        //top down
+        int vis_height = -1;
+        for(int y = 0; y < length; y++)
+        {
+            if (forest[x+y*length] > vis_height)
+            {
+                vis_height = forest[x+y*length];
+                visible[x+y*length] = true;
+            }
+        }
+
+        //bottom up
+        vis_height = -1;
+        for(int y = length-1; y >= 0; y--)
+        {
+            if (forest[x+y*length] > vis_height)
+            {
+                vis_height = forest[x+y*length];
+                visible[x+y*length] = true;
+            }
+        }
+    }
+
+    for(int y = 0; y < length; y++)
+    {
+        //Left right
+        int vis_height = -1;
+        for(int x = 0; x < length; x++)
+        {
+            if (forest[x+y*length] > vis_height)
+            {
+                vis_height = forest[x+y*length];
+                visible[x+y*length] = true;
+            }
+        }
+
+        //Right left
+        vis_height = -1;
+        for(int x = length-1; x >= 0; x--)
+        {
+            if (forest[x+y*length] > vis_height)
+            {
+                vis_height = forest[x+y*length];
+                visible[x+y*length] = true;
+            }
+        }
+    }
+
+    int total_vis = 0;
+    for(int i = 0; i < length*length; i++)
+    {
+        if(visible[i])
+        {
+            ++total_vis;
+        }
+    }
+
+    cout << total_vis << endl;
+
+    delete[] visible;
+    delete[] forest;
+}

Day8/part2.cpp

@@ -0,0 +1,83 @@
+#include <iostream>
+#include <string>
+
+using namespace std;
+
+int main(int argc, char* argv[])
+{
+    string line;
+    getline(cin, line);
+
+    int length = line.size();
+
+    int* forest = new int[length*length];
+    int in_y = 0;
+    do
+    {
+        for(int i = 0; i < length; i++)
+        {
+            forest[i+in_y*length] = line[i]-'0';
+        }
+        ++in_y;
+    } while(getline(cin, line));
+
+    int best_vis = 0;
+    for(int y = 0; y < length; y++)
+    {
+        for(int x = 0; x < length; x++)
+        {
+            int north_vis = 0;
+            int south_vis = 0;
+            int west_vis = 0;
+            int east_vis = 0;
+            int cur_vis = forest[x+y*length];;
+
+            for(int j = y-1; j >= 0; j--)
+            {
+                north_vis++;
+                if (forest[x+j*length] >= cur_vis)
+                {
+                    break;
+                }
+            }
+
+            for(int j = y+1; j < length; j++)
+            {
+                south_vis++;
+                if (forest[x+j*length] >= cur_vis)
+                {
+                    break;
+                }
+            }
+
+            for(int i = x-1; i >= 0; i--)
+            {
+                west_vis++;
+                if (forest[i+y*length] >= cur_vis)
+                {
+                    break;
+                }
+            }
+
+            for(int i = x+1; i<length; i++)
+            {
+                east_vis++;
+                if(forest[i+y*length] >= cur_vis)
+                {
+                    break;
+                }
+            }
+
+            int total_vis = north_vis*south_vis*east_vis*west_vis;
+
+            if (total_vis > best_vis)
+            {
+                best_vis = total_vis;
+            }
+        }
+    }
+
+    cout << best_vis << endl;
+
+    delete[] forest;
+}

Day9/part1.cpp

@@ -0,0 +1,94 @@
+#include <iostream>
+#include <string>
+#include <set>
+#include <utility>
+
+using namespace std;
+
+struct Rope
+{
+    Rope(pair<int, int> head, pair<int, int> tail) : head{head}, tail{tail} {}
+    pair<int, int> head, tail;
+
+};
+
+Rope move_rope(Rope rope, int dx, int dy);
+
+int main(int argc, char* argv[])
+{
+    Rope rope({0,0}, {0,0});
+    set<pair<int, int>> visited;
+
+    string line;
+    while(getline(cin, line))
+    {
+        char dir = line[0];
+        int amount = stoi(line.substr(2));
+        int dx = (dir=='R')?1:((dir=='L')?-1:0);
+        int dy = (dir=='U')?1:((dir=='D')?-1:0);
+
+        for(int i = 0; i < amount; i++)
+        {
+            rope = move_rope(rope, dx, dy);
+            visited.insert(rope.tail);
+        }
+    }
+
+    cout << visited.size() << endl;
+}
+
+Rope move_rope(Rope rope, int dx, int dy)
+{
+    rope.head.first += dx;
+    rope.head.second += dy;
+
+    if (rope.head.first == rope.tail.first)
+    { //same x
+        if (rope.head.second > rope.tail.second)
+        {
+            rope.tail.second = rope.head.second-1;
+        }
+        else if (rope.head.second < rope.tail.second)
+        {
+            rope.tail.second = rope.head.second+1;
+        }
+    }
+    else if (rope.head.second == rope.tail.second)
+    { //same y
+        if (rope.head.first > rope.tail.first)
+        {
+            rope.tail.first = rope.head.first-1;
+        }
+        else if (rope.head.first < rope.tail.first)
+        {
+            rope.tail.first = rope.head.first+1;
+        }
+    }
+    else
+    { //diagonal
+        if (abs(rope.head.first-rope.tail.first) == 1 && abs(rope.head.second-rope.tail.second) == 1)
+        {
+            return rope;
+        }
+
+        if (rope.head.first-rope.tail.first > 0)
+        {
+            rope.tail.first++;
+        }
+        else
+        {
+            rope.tail.first--;
+        }
+
+        if (rope.head.second-rope.tail.second > 0)
+        {
+            rope.tail.second++;
+        }
+        else
+        {
+            rope.tail.second--;
+        }
+    }
+
+    return rope;
+}

Day9/part2.cpp

@@ -0,0 +1,98 @@
+#include <iostream>
+#include <string>
+#include <set>
+#include <vector>
+#include <utility>
+
+using namespace std;
+
+void move_rope(pair<int, int>* head, pair<int, int>* tail);
+
+int main(int argc, char* argv[])
+{
+    vector<pair<int,int>> rope;
+    for(int i = 0; i < 10; i++)
+    {
+        rope.push_back({0,0});
+    }
+
+    set<pair<int, int>> visited;
+
+    string line;
+    while(getline(cin, line))
+    {
+        char dir = line[0];
+        int amount = stoi(line.substr(2));
+        int dx = (dir=='R')?1:((dir=='L')?-1:0);
+        int dy = (dir=='U')?1:((dir=='D')?-1:0);
+
+        for(int i = 0; i < amount; i++)
+        {
+            rope[0].first += dx;
+            rope[0].second += dy;
+
+            vector<pair<int,int>>::iterator knot1 = rope.begin();
+            vector<pair<int,int>>::iterator knot2 = rope.begin()+1;
+            for(int j = 0; j < rope.size(); j++)
+            {
+                move_rope(&(*knot1), &(*knot2));
+                ++knot1;
+                ++knot2;
+            }
+            visited.insert(rope.back());
+        }
+    }
+
+    cout << visited.size() << endl;
+}
+
+void move_rope(pair<int, int>* head, pair<int, int>* tail)
+{
+    if (head->first == tail->first)
+    { //same x
+        if (head->second > tail->second)
+        {
+            tail->second = head->second-1;
+        }
+        else if (head->second < tail->second)
+        {
+            tail->second = head->second+1;
+        }
+    }
+    else if (head->second == tail->second)
+    { //same y
+        if (head->first > tail->first)
+        {
+            tail->first = head->first-1;
+        }
+        else if (head->first < tail->first)
+        {
+            tail->first = head->first+1;
+        }
+    }
+    else
+    { //diagonal
+        if (abs(head->first-tail->first) == 1 && abs(head->second-tail->second) == 1)
+        {
+            return;
+        }
+
+        if (head->first-tail->first > 0)
+        {
+            tail->first++;
+        }
+        else
+        {
+            tail->first--;
+        }
+
+        if (head->second-tail->second > 0)
+        {
+            tail->second++;
+        }
+        else
+        {
+            tail->second--;
+        }
+    }
+}

README.md

@@ -2,12 +2,6 @@
 
 Advent of Code for 2022
 
-## How to contribute
+# Branch format
 
-To contribute to the Advent of Code 2022, please pull master and create a branch with your name.
+Uploading code files at partX.cpp in each day's folder. Compile the part with `g++ partX.cpp -o partX`. Download your input file as `inputX` and run the program with `./partX < inputX`.
-
-Recommended folder structure is `{Day}\{Language}\{Part}`
-
-## Tips
-
-It is recommended to include small document on how the program works and how to compile & run the program.