POJ 1979 Red and Black DFS

简单DFS。

//#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<iostream>
#include<sstream>
#include<cmath>
#include<climits>
#include<string>
#include<map>
#include<queue>
#include<vector>
#include<stack>
#include<set>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
#define pb(a) push(a)
#define INF 0x1f1f1f1f
#define lson idx<<1,l,mid
#define rson idx<<1|1,mid+1,r
#define PI  3.1415926535898
template<class T> T min(const T& a,const T& b,const T& c) {
    return min(min(a,b),min(a,c));
}
template<class T> T max(const T& a,const T& b,const T& c) {
    return max(max(a,b),max(a,c));
}
void debug() {
#ifdef ONLINE_JUDGE
#else

    freopen("in.txt","r",stdin);
    //freopen("d:\\out1.txt","w",stdout);
#endif
}
int getch() {
    int ch;
    while((ch=getchar())!=EOF) {
        if(ch!=' '&&ch!='\n')return ch;
    }
    return EOF;
}

const int maxn=25;
char g[maxn][maxn];
int dx[]={0,0,1,-1};
int dy[]={1,-1,0,0};

int vis[maxn][maxn];
void dfs(int x,int y,int &num)
{
    num++;
    vis[x][y]=1;
    for(int d=0;d<4;d++)
    {
        int nx=x+dx[d];
        int ny=y+dy[d];
        if(g[nx][ny]=='.'&&!vis[nx][ny])
            dfs(nx,ny,num);
    }
}

int main()
{
    int n,m;
    while(scanf("%d%d",&m,&n)!=EOF&&n)
    {
        memset(g,'#',sizeof(g));
        for(int i=1;i<=n;i++)
            scanf("%s",g[i]+1);
        int num=0;
        memset(vis,0,sizeof(vis));
        for(int i=1;i<=n;i++)
            for(int j=1;j<=m;j++)
                if(g[i][j]=='@')
                    dfs(i,j,num);
        printf("%d\n",num);
    }
    return 0;
}