floyd到其它所有点的最小值，求一个最大值

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

const int N = 110;
int d[N][N];
int n,m;

int main()
{
    cin>>n>>m;
    memset(d,0x3f,sizeof d);

    for(int i = 1;i<=n;i++)d[i][i] = 0;
    while(m--)
    {
        int a,b,c;
        cin>>a>>b>>c;
        d[a][b] = d[b][a] = min(d[a][b],c);
    }

    for(int k = 1;k<=n;k++)
        for(int i = 1;i<=n;i++)
            for(int j = 1;j<=n;j++)
                d[i][j] = min(d[i][j],d[i][k]+d[k][j]);

    int res = 0;
    for(int i = 1;i<=n;i++)
    {
        if(d[1][i] == 0x3f3f3f3f)
        {
            res = -1;
            break;
        }
        else
        {
            res = max(res,d[1][i]);
        }
    }
    cout<<res<<endl;
}