hdu1599 find the mincost route

题目链接

floyd找最小环

很好理解

 #include<algorithm>
 #include<iostream>
 #include<cstdlib>
 #include<cstring>
 #include<cstdio>
 #include<string>
 #include<cmath>
 #include<ctime>
 #include<queue>
 #include<stack>
 #include<map>
 #include<set>
 #define rre(i,r,l) for(int i=(r);i>=(l);i--)
 #define re(i,l,r) for(int i=(l);i<=(r);i++)
 #define Clear(a,b) memset(a,b,sizeof(a))
 #define inout(x) printf("%d",(x))
 #define douin(x) scanf("%lf",&x)
 #define strin(x) scanf("%s",(x))
 #define LLin(x) scanf("%lld",&x)
 #define op operator
 #define CSC main
 typedef unsigned long long ULL;
 typedef const int cint;
 typedef long long LL;
 using namespace std;
 cint inf=;
 void inin(int &ret)
 {
     ret=;int f=;char ch=getchar();
     while(ch<''||ch>''){if(ch=='-')f=;ch=getchar();}
     while(ch>=''&&ch<='')ret*=,ret+=ch-'',ch=getchar();
     ret=f?-ret:ret;
 }
 int n,m,t,dis[][],mp[][];
 int floyd()
 {
     int ret=inf;
     re(k,,n)
     {
         re(i,,n)if(i!=k)
             re(j,,n)if(j!=k&&j!=i)
                 if(dis[i][j]<inf&&mp[i][k]!=inf&&mp[k][j]!=inf)
                     ret=min(ret,mp[i][k]+mp[k][j]+dis[i][j]);
         re(i,,n)
             re(j,,n)
                 dis[i][j]=min(dis[i][j],dis[i][k]+dis[k][j]);
     }
     return ret;
 }
 int main()
 {
     while(scanf("%d%d",&n,&m)!=EOF)
     {
         re(i,,n)re(j,,m)dis[i][j]=mp[i][j]=inf;
         re(i,,m)
         {
             int q,w,e;inin(q),inin(w),inin(e);
             dis[q][w]=dis[w][q]=mp[q][w]=mp[w][q]=min(dis[q][w],e);
         }
         int ans=floyd();
         if(ans==inf)printf("It's impossible.\n");
         else printf("%d\n",ans);
     }
      return ;
 }