hdu1312

//简单搜索，只要走遍所有可达的路径

BFS版:

#include "iostream"
#include "cstdio"
#include "memory.h"
#include "queue"
using namespace std;
const int MAX = 22;
const int dx[] = {1,-1,0,0},dy[] = {0,0,1,-1};
char map[MAX][MAX];
int vis[MAX][MAX];
int x,y;
int n,m;
pair<int ,int> now;
int bfs()
{
    int cnt = 1;
    memset(vis,0,sizeof(vis));
    queue< pair<int,int> > que;
    que.push(make_pair(x,y));
    vis[x][y] = 1;
    while (!que.empty()) {
        now = que.front();
        que.pop();
        int i,tx,ty;
        for (i = 0;i < 4; ++ i) {
            tx = now.first + dx[i];
            ty = now.second + dy[i];
            if (tx < 0 || ty < 0|| tx >= m || ty >= n) continue;
            if (vis[tx][ty]) continue;
            if (map[tx][ty] == '.') {
                cnt++;
                que.push(make_pair(tx,ty));
            }
            vis[tx][ty] = 1;
        }
    }
    return cnt;
}
int main()
{
    int i,j;
    while (cin >> n >> m,m+n) {   //m行    n列
        for (i = 0; i < m; ++ i)
            for (j = 0;j < n ; ++ j) {
                cin >> map[i][j];
                if (map[i][j] == '@')
                    x = i,y = j;
            }
            //cout << x << " " << y << endl;
            cout << bfs() << endl;

    }
    return 0;
}


DFS：

#include "iostream"
#include "cstdio"
#include "memory.h"
#include "queue"
using namespace std;
const int MAX = 22;
const int dx[] = {1,-1,0,0},dy[] = {0,0,1,-1};
char map[MAX][MAX];
int vis[MAX][MAX];
int x,y;
int n,m;
int cnt;
void dfs(int x,int y)
{
    vis[x][y] = 1;
    int i, tx, ty;
    for (i = 0;i < 4 ; ++i) {
        tx = x + dx[i];
        ty = y + dy[i];
        if (tx >= 0 && ty >= 0 && tx < m && ty < n && map[tx][ty] != '#' && !vis[tx][ty]) {
                cnt ++;
                dfs(tx,ty);
        }
    }
}
int main()
{
    int i,j;
    while (cin >> n >> m,m+n) {   //m行    n列
        for (i = 0; i < m; ++ i)
            for (j = 0;j < n ; ++ j) {
                cin >> map[i][j];
                if (map[i][j] == '@')
                    x = i,y = j;
            }
            cnt = 1;
            dfs(x,y);
            cout << cnt << endl;
        memset(vis,0,sizeof(vis));
    }
    return 0;
}