diff options
| -rw-r--r-- | 2021/day09.c | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/2021/day09.c b/2021/day09.c new file mode 100644 index 0000000..44c20a1 --- /dev/null +++ b/2021/day09.c @@ -0,0 +1,34 @@ +#include <stdio.h> +#include <stdlib.h> +static int h, w; +static int grid[128][128]; +static int adj(int *a, int y, int x) { + int n = 0; + if (y > 0) a[n++] = grid[y-1][x]; + if (y < h-1) a[n++] = grid[y+1][x]; + if (x > 0) a[n++] = grid[y][x-1]; + if (x < w-1) a[n++] = grid[y][x+1]; + return n; +} +int main(void) { + size_t cap = 0; + char *buf = NULL; + while (0 < getline(&buf, &cap, stdin)) { + for (w = 0; buf[w] && buf[w] != '\n'; ++w) { + grid[h][w] = buf[w] - '0'; + } + h++; + } + int risk = 0; + for (int y = 0; y < h; ++y) + for (int x = 0; x < w; ++x) { + int a[4]; + int n = adj(a, y, x); + int m = 0; + for (int i = 0; i < n; ++i) { + if (a[i] <= grid[y][x]) m |= 1; + } + if (!m) risk += 1 + grid[y][x]; + } + printf("%d\n", risk); +} |