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; }