poj 1979 dfs

水过。注意边界不能超出。

#include <iostream>
using namespace std;
int n, m, sx, sy, dir[4][2] = {0, -1, 0, 1, 1, 0, -1, 0}, count;
char diagram[23][23];

void get_diagram(void) {
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            cin >> diagram[i][j];
            if (diagram[i][j] == '@') {
                sx = i;
                sy = j;
            }
        }
    }
}

void dfs(int x, int y) {
    count++;
    diagram[x][y] = '#';
    for (int i = 0; i < 4; i++) {
        if (x + dir[i][0] >=0 && x + dir[i][0] < n && y + dir[i][1] >= 0 && y + dir[i][1] < m && diagram[x + dir[i][0]][y + dir[i][1]] != '#') {
            dfs(x + dir[i][0], y + dir[i][1]);
        }
    }
    return;
}

int main(void) {
    while (cin >> m >> n, n*n + m*m) {
        get_diagram();
        count = 0;
        dfs(sx, sy);
        cout << count << endl;
    }
    return 0;
}