2021 day5 part1

1 files changed, 93 insertions, 0 deletions

diff --git a/src/2021/day5/aoc.cpp b/src/2021/day5/aoc.cpp
index 7a3c895..47cc423 100644
--- a/src/2021/day5/aoc.cpp
+++ b/src/2021/day5/aoc.cpp
@@ -1,5 +1,98 @@
 #include "aoc.h"
+#include <algorithm>
+#include <vector>
 
 namespace aoc2021 {
 
+static void get_number(const char** pp, int* d) {
+  *d = 0;
+  const char* p = *pp;
+  while (*p >= '0' && *p <= '9') {
+    *d = *d * 10 + *p - '0';
+    p++;
+  }
+  *pp = p;
 }
+
+void fill(std::vector<int>& b1, std::vector<int>& b2, const line& l, int width) {
+  int maxx = std::max(l.p1.x, l.p2.x);
+  int minx = std::min(l.p1.x, l.p2.x);
+  int maxy = std::max(l.p1.y, l.p2.y);
+  int miny = std::min(l.p1.y, l.p2.y);
+
+  if (l.p1.x == l.p2.x || l.p1.y == l.p2.y) {
+    for (int i = minx; i <= maxx; i++) {
+      for (int j = miny; j <= maxy; j++) {
+        // printf("[%d, %d]\n", i, j);
+        b1[j * width + i] += 1;
+        b2[j * width + i] += 1;
+        if (b2[j * width + i] > 1) {
+          printf("[%d, %d]\n", i, j);
+        }
+      }
+    }
+  }
+
+  if (l.p1.x == l.p1.y && l.p2.x == l.p2.y) {
+    int j = miny;
+    for (int i = minx; i <= maxx; i++) {
+      b2[j * width + i] += 1;
+      if (b2[j * width + i] > 1) {
+        printf("[%d, %d]\n", i, j);
+      }
+      j++;
+    }
+  }
+
+  if (l.p1.x == l.p2.y && l.p2.x == l.p1.y) {
+    int j = maxy;
+    for (int i = minx; i <= maxx; i++) {
+      b2[j * width + i] += 1;
+      if (b2[j * width + i] > 1) {
+        printf("[%d, %d]\n", i, j);
+      }
+      j--;
+    }
+  }
+}
+
+std::pair<int, int> day5(line_view file) {
+  std::vector<line> vs;
+  int maxx{INT32_MIN};
+  int maxy{INT32_MIN};
+
+  per_line(file, [&vs, &maxx, &maxy](line_view lv) {
+    line l;
+    int* is[] = {&l.p1.x, &l.p1.y, &l.p2.x, &l.p2.y};
+    const char* p = lv.line;
+    int i{0};
+    while (p < lv.line + lv.length) {
+      if (*p >= '0' && *p <= '9') {
+        get_number(&p, is[i++]);
+      }
+      p++;
+    }
+    maxx = std::max(maxx, std::max(l.p1.x, l.p2.x));
+    maxy = std::max(maxy, std::max(l.p1.y, l.p2.y));
+    vs.push_back(l);
+    return true;
+  });
+
+  maxx += 1;
+  maxy += 1;
+
+  printf("%d, %d\n", maxx, maxy);
+  std::vector<int> board1(maxx * maxy, 0);
+  std::vector<int> board2(maxx * maxy, 0);
+  for (auto& l : vs) {
+    fill(board1, board2, l, maxx);
+  }
+
+  int t1{0};
+  int t2{0};
+  std::for_each(board1.begin(), board1.end(), [&t1](int x) { t1 += int(x >= 2); });
+  std::for_each(board2.begin(), board2.end(), [&t2](int x) { t2 += int(x >= 2); });
+  return {t1, t2};
+}
+
+} // namespace aoc2021