学步园

最小生成树入门题，套模版就可以

不明白为什么我写的最小生成树这么慢，限时2000，我跑了1047ms

code

/*
    ID:yueqiq1
    LANG:C++
    PROB:
*/
#include <set>
#include <map>
#include <ctime>
#include <queue>
#include <cmath>
#include <stack>
#include <limits>
#include <vector>
#include <bitset>
#include <string>
#include <cstdio>
#include <cstring>
#include <fstream>
#include <string.h>
#include <iostream>
#include <algorithm>
#define Si set<int>
#define LL long long
#define pb push_back
#define PS printf(" ")
#define Vi vector<int>
#define LN printf("\n")
#define lson l,m,rt << 1
#define rson m+1,r,rt<<1|1
#define SD(a) scanf("%d",&a)
#define PD(a) printf("%d",a)
#define SET(a,b) memset(a,b,sizeof(a))
#define FF(i,a) for(int i(0);i<(a);i++)
#define FD(i,a) for(int i(a);i>=(1);i--)
#define FOR(i,a,b) for(int i(a);i<=(b);i++)
#define FOD(i,a,b) for(int i(a);i>=(b);i--)
#define readf freopen("input.txt","r",stdin)
#define writef freopen("output.txt","w",stdout)
const int maxn = 2001;
const int INF = 0x3fffffff;
const int dx[]={0,1,0,-1};
const int dy[]={1,0,-1,0};
const double pi = acos(-1.0);
using namespace std;
int N;
char str[maxn][7];
int edge[maxn][maxn], dis[maxn];
bool vis[maxn];
int get_w(int x,int y){
    int ans=0;
    FF(i,7){
        if(str[x][i]!=str[y][i])
            ans++;
    }
    return ans;
}
int prim(){
    int ans=0;
    SET(vis,false);
    //默认任意点为1
    FOR(i,1,N) dis[i]=edge[1][i];
//    FOR(i,1,N){
//        printf("dis[%d] ==  %d\n",i,dis[i]);
//    }
    vis[1]=true;
    int k=1;
    FF(i,N-1){
        int tmp=INF;
        FOR(j,1,N){
            if(!vis[j] && dis[j]<tmp){
                tmp=dis[j];
                k=j;
            }
        }
//        printf("the k is:%d    tmp:%d \n",k,tmp);
        ans+=tmp;
        vis[k]=true;

        FOR(j,1,N){
            if(!vis[j] && edge[k][j]< dis[j])
                dis[j]=edge[k][j];
        }
    }
    return ans;
}
int main(){

    while(~SD(N) && N){
        SET(edge,0);
        FOR(i,1,N) scanf("%s",str[i]);
        FOR(i,1,N-1) FOR(j,1,N) edge[i][j]=edge[j][i]=get_w(i,j);
        printf("The highest possible quality is 1/%d.\n",prim());
    }
	return 0;
}