1 files changed, 77 insertions, 2 deletions
diff --git a/src/2017/day10/aoc.cpp b/src/2017/day10/aoc.cpp
index b6b617f..0d0d5a4 100644
--- a/src/2017/day10/aoc.cpp
+++ b/src/2017/day10/aoc.cpp
@@ -1,4 +1,6 @@
 #include "aoc.h"
+#include <deque>
+#include <set>
 
 namespace aoc2017 {
 
@@ -102,7 +104,19 @@ static void reduce(uint8_t dense[16], uint8_t sparse[256]) {
   }
 }
 
-int knot_hash(line_view file, int total) {
+static void binary_grid(char hexdigit[33], char* grid) {
+  const char* b09[] = {"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001"};
+  const char* baf[] = {"1010", "1011", "1100", "1101", "1110", "1111"};
+
+  for (int i = 0; i < 32; i++) {
+    char c = hexdigit[i];
+    memcpy(grid + 4 * i, c >= '0' && c <= '9' ? b09[c - '0'] : baf[c - 'a'], 4);
+  }
+
+  // printf("%s\n", binary);
+}
+
+int knot_hash(line_view file, int total, char* grid = nullptr) {
   const char trail[] = {17, 31, 73, 47, 23};
   char* input = (char*)malloc(file.length - 1 + 5);
   memcpy(input, file.line, file.length - 1);
@@ -125,8 +139,10 @@ int knot_hash(line_view file, int total) {
   for (int i = 0; i < 16; i++) {
     sprintf(hexdigit + i * 2, "%02x", dense[i]);
   }
-  // printf("%s\n", hexdigit);
 
+  if (grid != nullptr) {
+    binary_grid(hexdigit, grid);
+  }
   return 0;
 }
 
@@ -134,4 +150,63 @@ std::pair<int64_t, int64_t> day10(line_view file) {
   knot_hash(file, 64);
   return {knot_hash_once(file), 0};
 }
+
+struct pos {
+  int r;
+  int c;
+
+  friend bool operator==(pos p1, pos p2) { return p1.r == p2.r && p1.c == p2.c; }
+  friend bool operator<(pos p1, pos p2) { return p1.r < p2.r ? true : p1.r > p2.r ? false : p1.c < p2.c; }
+};
+
+void floodfill(int x, pos p, char grid[128][128], int fill[128][128]) {
+  std::deque<pos> q;
+  q.push_back(p);
+
+  auto is_valid = [](pos p) -> bool { return p.r >= 0 && p.r < 128 && p.c >= 0 && p.c < 128; };
+  while (!q.empty()) {
+    auto s = q.size();
+    while (s-- > 0) {
+      auto p0 = q.front();
+      q.pop_front();
+
+      fill[p0.r][p0.c] = x;
+
+      pos ns[] = {{p0.r, p0.c + 1}, {p0.r, p0.c - 1}, {p0.r - 1, p0.c}, {p0.r + 1, p0.c}};
+      for (auto& n : ns) {
+        if (is_valid(n) && grid[n.r][n.c] == '1' && fill[n.r][n.c] == 0) {
+          q.push_back(n);
+        }
+      }
+    }
+  }
+}
+
+std::pair<int64_t, int64_t> day14(line_view) {
+  char buf[30];
+  const char* key = "oundnydw";
+  // const char* key = "flqrgnkx";
+  char grid[128][128];
+  for (int i = 0; i < 128; i++) {
+    memset(buf, 0, 30);
+    sprintf(buf, "%s-%d\n", key, i);
+    knot_hash(buf, 64, grid[i]);
+  }
+
+  int t0{0};
+  int fill[128][128] = {{0}};
+
+  int t1{0};
+  for (int r = 0; r < 128; r++) {
+    for (int c = 0; c < 128; c++) {
+      char x = grid[r][c];
+      t0 += x - '0';
+      if (x == '1' && fill[r][c] == 0) {
+        floodfill(++t1, {r, c}, grid, fill);
+      }
+    }
+  }
+
+  return {t0, t1};
+}
 } // namespace aoc2017