这道题写prim的时候wa了一次，又找了半个小时的错，最后发现竟然是上次写题的时候把INF给改小了 我晕
prim ：
/*
ID: yueqiq
PROG: numtri
LANG: C++
*/
#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 = 501;
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;
//prim
int N;
int edge[maxn][maxn],dis[maxn];
bool vis[maxn];
int prim(){
SET(vis,false);
FOR(i,1,N) dis[i]=edge[1][i];
//FOR(i,1,N) printf("dis[%d]==%d\n",i,dis[i]);
int s=1;// 任意选出一点，默认为第一个
vis[s]=true;
int minn;
int ans=-INF;
FOR(i,1,N-1){
minn=INF;
FOR(j,1,N){
if(!vis[j] && dis[j]<minn){
minn=dis[j];
s=j;
}
}
//printf("the s is:%d the min is:%d\n",s,minn);
if(minn>ans)
ans=minn;
vis[s]=true;
FOR(j,1,N){
if(!vis[j] && dis[j]>edge[s][j])
dis[j]=edge[s][j];
}
}
return ans;
}
int main()
{
int cas;
SD(cas);
while(cas--){
SD(N);
FOR(i,1,N) FOR(j,1,N) edge[i][j]=INF;
FOR(i,1,N) FOR(j,1,N){
SD(edge[i][j]);
}
// FOR(i,1,N) FOR(j,1,N){
// printf("i:%d j:%d edge:%d\n",i,j,edge[i][j]);
// }
PD(prim());LN;
}
return 0;
}