POJ-1979 Red and Black（DFS）

题目链接：http://poj.org/problem?id=1979

深度优先搜索非递归写法

#include <cstdio>
#include <stack>

using namespace std;
const int MAX_W = , MAX_H = ;
char Map[MAX_W][MAX_H+];
int W, H;

int DFS(int sx, int sy);

int main()
{
    while (scanf("%d %d", &H, &W) ==
           && W !=  && H != ) {
        for (int i = ; i < W; i++)
            scanf("%s", Map[i]);
        for (int i = ; i < W; i++)
            for (int j = ; j < H; j++) {
                if (Map[i][j] == '@')
                    printf("%d\n", DFS(i, j));
            }
    }
    return ;
}

int DFS(int sx, int sy)
{
    int dx[] = {, , -, }, dy[] = {, , , -};
    int Visited[MAX_W][MAX_H] = {};
    typedef pair<int, int> Position;
    stack<Position> sta;

    Visited[sx][sy] = ;
    int num = ;
    Map[sx][sy] = '.';
    sta.push(Position(sx, sy));

    while (!sta.empty()) {
        Position p = sta.top(); sta.pop();
        for (int i = ; i < ; i++) {
            int nx = p.first + dx[i], ny = p.second + dy[i];
            if ( <= nx && nx < W &&  <= ny && ny < H &&
                Map[nx][ny] == '.' && !Visited[nx][ny]) {
                sta.push(Position(nx, ny));
                Visited[nx][ny] = ;
                num++;
            }
        }
    }
    return num;
}