Day 10

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;
+            }
+        }
+    }
+}

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--;
+        }
+    }
+}