AOJ 1130 Red and Black Time Limit : 1 sec, Memory Limit : 65536 KB

AOJ_1130_dfs.cpp

// 縦型探索
#include <iostream>
#include <string>
#include <vector>

using namespace std;

int w, h;
int mx[] = {0, 0, -1, 1};
int my[] = {-1, 1, 0, 0};

int dfs(int x, int y, vector<string> &v) {
    int cnt = 1;
    for ( int i = 0; i < 4; i++ ) {
        int nx = x + mx[i], ny = y + my[i];
        if ( 0 <= nx && nx < w && 0 <= ny && ny < h && v[ny][nx] == '.' ) {
            v[ny][nx] = '#';
            cnt += dfs(nx, ny, v);
        }
    }
    return cnt;
}

int main() {
    while ( true ) {
        int x, y;
        cin >> w >> h;
        if ( w == 0 && h == 0 ) break;

        vector<string> v(h);

        for ( int i = 0; i < h; i++ ) {
            cin >> v[i];

            for ( int j = 0; j < v[i].size(); j++ ) {
                if ( v[i][j] == '@' ) {
                    y = i;
                    x = j;
                }
            }
        }

        cout << dfs(x, y, v) << endl;
    }
    return 0;
}