[kuangbin带你飞]专题四 最短路练习 G MPI Maelstrom

#include<iostream>
#include<cstring>
#include<algorithm>
#include<iomanip>
#include<cmath>
#include<cstdio>
#include<vector>
using namespace std;
#define MAXN 101
#define INF 0x3f3f3f3f
/*
8:19
8:35 题意理解太慢：在所有最短路路中间一条最长的
8:52 sscanf用法
8:57 忘记BEEN,g[i][j] = g[j][i]双向
*/
int n;
bool been[MAXN];
int g[MAXN][MAXN],lowcost[MAXN];
int Dijkstra()
{
    memset(lowcost,INF,sizeof(lowcost));
    memset(been,false,sizeof(been));
    lowcost[1] = 0;
    for(int j=0;j<n;j++)
    {
        int Min = INF,k = -1;
        for(int i=1;i<=n;i++)
        {
            if(!been[i]&&lowcost[i]<Min)
            {
                Min = lowcost[i];
                k = i;
            }
        }
        if(k==-1) break;
        been[k] = true;
        for(int i=1;i<=n;i++)
        {
            if(!been[i]&&lowcost[i]>lowcost[k]+g[k][i])
            {
                lowcost[i] = lowcost[k]+g[k][i];
            }
        }
    }
    int Max = -1;
    for(int i=1;i<=n;i++)
    {
        Max = max(Max,lowcost[i]);
    }
    return Max;
}
int main()
{
    cin>>n;
    char s[30];
    memset(g,INF,sizeof(g));
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<i;j++)
        {
            cin>>s;
            if(s[0]=='x')
            {
                g[i][j] = g[j][i]= INF;
            }
            else
            {
                sscanf(s,"%d",&g[i][j]);
                g[j][i] = g[i][j];
            }
        }
    }
    int ans =Dijkstra();
    cout<<ans<<endl;
    return 0;
}