BFS

#include<stdio.h>struct note{int x;int y;};int main(){struct note que[2501];int head, tail;int a[51][51];int book[51][51] = { 0 };int i, j, k, sum, max = 0, mx, my, n, m, startx, starty, tx, ty;int next[4][2] = { { 0, 1 }, { 1, 0 }, { 0, -1 }, { -1, 0 } };scanf("%d%d%d", &n,&m,&startx, &starty);for (i = 1; i <= n; i++){for (j = 1; j <= n; j++){scanf("%d", &a[i][j]);}}head = 1;tail = 1;que[tail].x = startx;que[tail].y = starty;tail++;book[startx][starty] = 1;sum = 1;while (head < tail){for (k = 0; k < 3; k++){tx = que[head].x + next[k][0];ty = que[head].y + next[k][1];if (tx<1 || tx>n || ty<1 || ty>m){continue;}if (a[tx][ty]>0 && book[tx][ty] == 0){sum++;book[tx][ty] = 1;que[tail].x = tx;que[tail].y = ty;tail++;}}head++;}printf("%d\n", sum);return 0;}