[hdu 2102]bfs+注意INF

Posted 2020-10-05 ACMsong

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=2102

感觉这个题非常水，结果一直WA，最后发现居然是0x3f3f3f3f不够大导致的……把INF改成INF+INF就过了。

#include<bits/stdc++.h>
using namespace std;

bool vis[2][15][15];
char s[2][15][15];
const int INF=0x3f3f3f3f;

const int fx[]={0,0,1,-1};
const int fy[]={1,-1,0,0};

int bfs()
{
    memset(vis,false,sizeof(vis));
    queue< pair<int,int> > q;
    while (!q.empty()) q.pop();
    q.push(make_pair(0*10000+1*100+1,0));
    vis[0][1][1]=true;
    while (!q.empty())
    {
        int layer=q.front().first/10000;
        int x=q.front().first%10000/100;
        int y=q.front().first%100;
        int st=q.front().second;
        q.pop();
        for (int i=0;i<4;i++)
        {
            int xx=x+fx[i];
            int yy=y+fy[i];
            if (s[layer][xx][yy]!=‘*‘ && !vis[layer][xx][yy])
            {
                if (s[layer][xx][yy]==‘P‘ || (s[layer][xx][yy]==‘#‘ && s[layer^1][xx][yy]==‘P‘)) return st+1;
                if (s[layer][xx][yy]==‘#‘ && !vis[layer^1][xx][yy])
                {
                    vis[layer][xx][yy]=vis[layer^1][xx][yy]=true;
                    q.push(make_pair((layer^1)*10000+xx*100+yy,st+1));
                }
                if (s[layer][xx][yy]==‘.‘ || s[layer][xx][yy]==‘S‘)
                {
                    vis[layer][xx][yy]=true;
                    q.push(make_pair(layer*10000+xx*100+yy,st+1));
                }
            }
        }
    }
    return INF+INF;
}

int main()
{
    int T;
    scanf("%d",&T);
    while (T--)
    {
        memset(s,‘*‘,sizeof(s));
        int n,m,t;
        cin >>n >>m >>t;
        for (int _=0;_<2;_++)
            for (int i=1;i<=n;i++)
                for (int j=1;j<=m;j++)
                    cin >>s[_][i][j];
        for (int i=1;i<=n;i++)
            for (int j=1;j<=m;j++)
                if (s[0][i][j]==‘#‘&&s[1][i][j]==‘#‘ || s[0][i][j]==‘#‘&&s[1][i][j]==‘*‘ || s[0][i][j]==‘*‘&&s[1][i][j]==‘#‘) s[0][i][j]=s[1][i][j]=‘*‘;
        if (bfs()<=t) cout <<"YES" <<endl;
        else cout <<"NO" <<endl;
    }
    return 0;
}