60分代码：

#include<bits/stdc++.h>
using namespace std;
int n, m, dis[110][110]; 
const int inf = 1e9;
void add_edge (int u, int v, int w)
{
	dis[u][v] = dis[v][u] = min(dis[u][v], w);
}
int main()
{
	cin >> n >> m;
	for (int i = 1; i <= n; i++)
		for (int j = 1; j <= n; j++)
			dis[i][j] = inf;
	for (int i = 1; i <= n; i++)
		dis[i][i] = 0;
	for (int i = 1, u, v, w; i <= m; i++)
		scanf ("%d%d%d", &u, &v, &w), add_edge (u, v, w);
	for (int i = 1; i <= n; i++)//起点 
		for (int j = 1; j <= n; j++)//终点 
			for (int k = 1; k <= n; k++)//中间点
				if (dis[i][k] != inf && dis[k][j] != inf)
					dis[i][j] = min (dis[i][j], dis[i][k] + dis[k][j]);
	for (int i = 1; i <= n; i++)
	{
		for (int j = 1; j <= n; j++)
			cout << dis[i][j] << " ";
		cout << endl;
	}
    return 0;
}

AC代码：

#include<bits/stdc++.h>
using namespace std;
int n, m, dis[110][110]; 
const int inf = 1e9;
void add_edge (int u, int v, int w)
{
	dis[u][v] = min (dis[u][v], w);
	dis[v][u] = min (dis[v][u], w);
}
int main()
{
	cin >> n >> m;
	for (int i = 1; i <= n; i++)
		for (int j = 1; j <= n; j++)
			dis[i][j] = inf;
	for (int i = 1; i <= n; i++)
		dis[i][i] = 0;
	for (int i = 1, u, v, w; i <= m; i++)
		scanf ("%d%d%d", &u, &v, &w), add_edge (u, v, w);
	for (int k = 1; k <= n; k++)//中间点
		for (int i = 1; i <= n; i++)//起点 
			for (int j = 1; j <= n; j++)//终点 
				if (dis[i][k] != inf && dis[k][j] != inf)
					dis[i][j] = min (dis[i][j], dis[i][k] + dis[k][j]);
	for (int i = 1; i <= n; i++)
	{
		for (int j = 1; j <= n; j++)
			cout << dis[i][j] << " ";
		cout << endl;
	}
    return 0;
}

改了个顺序就过了，为啥？