POJ Borg Maze (BFS+最小生成树)

#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<cstdio>
#include<string>
#include<iostream>
#include<cstring>
#include<cmath>
#include<stack>
#include<queue>
#include<vector>
#include<map>
#include<stdlib.h>
#include<algorithm>
#define LL __int64
using namespace std;
const int MAXN=100+5;
const int INF=0x3f3f3f3f;
int kase,n,m,tot;
char mat[MAXN][MAXN];
int a[MAXN][MAXN];
int w[MAXN][MAXN];
int wis[MAXN*MAXN];
int vis[MAXN][MAXN];
int d[MAXN];
int dir[4][2]={{0,1},{1,0},{0,-1},{-1,0}};
char opt[10];
struct node
{
    int x,y;
    int step;
}s;
void BFS(int sx,int sy)
{
    memset(vis,0,sizeof(vis));
    queue<node> Q;
    while(!Q.empty()) Q.pop();
    s.x=sx,s.y=sy,s.step=0;
    vis[sx][sy]=1;
    Q.push(s);
    while(!Q.empty())
    {
        node now,next;
        now=Q.front();Q.pop();
//        printf("%d %d\n",now.x,now.y);
        if(mat[now.x][now.y]==‘A‘ || mat[now.x][now.y]==‘S‘)
            w[a[sx][sy]][a[now.x][now.y]]=now.step;

        for(int i=0;i<4;i++)
        {
            next.x=now.x+dir[i][0];
            next.y=now.y+dir[i][1];
            if(mat[next.x][next.y]!=‘#‘ && !vis[next.x][next.y] && 1<=next.x && next.x<=n && 1<=next.y && next.y<=m)
            {
                next.step=now.step+1;
                vis[next.x][next.y]=1;
                Q.push(next);
            }
        }
    }
}
void prim()
{
    memset(wis,0,sizeof(wis));
    for(int i=2;i<tot;i++) d[i]=w[1][i];
    wis[1]=1;
    int ans=0;

    for(int i=1;i<tot-1;i++)
    {
        int tmp,minn=INF;
        for(int j=1;j<tot;j++)
        {
            if(!wis[j] && d[j]<minn)
            {
                minn=d[j];
                tmp=j;
            }
        }
        if(minn==INF) break;
        wis[tmp]=1;
        ans+=minn;
        for(int j=1;j<tot;j++)
            if(!wis[j] && w[tmp][j]<d[j])
                d[j]=w[tmp][j];
    }
    printf("%d\n",ans);
}
int main()
{
    //freopen("in.txt","r",stdin);
    scanf("%d",&kase);
    while(kase--)
    {
        memset(w,0,sizeof(w));
        scanf("%d %d",&m,&n);
        gets(mat[0]);
        tot=1;
        memset(a,-1,sizeof(a));

        for(int i=1;i<=n;i++)
        {
            gets(mat[i]+1);
            printf("%s",mat[i]);
            for(int j=1;j<=m;j++)
                if(mat[i][j]==‘A‘ || mat[i][j]==‘S‘)
                    a[i][j]=tot++;
        }

        for(int i=1;i<=n;i++)
            for(int j=1;j<=m;j++)
                if(a[i][j]!=-1)
                    BFS(i,j);

        prim();
    }
    return 0;
}