Codeforces 459E Pashmak and Graph

http://www.codeforces.com/problemset/problem/459/E

题意:

给出n个点,m条边的有向图，每个边有边权，求一条最长的边权上升的路径的长度。

思路:用f存边，g存点，然后排序转移，注意相同的要延迟转移

 #include<cstdio>
 #include<cmath>
 #include<algorithm>
 #include<cstring>
 #include<iostream>
 struct edge{
     int u,v,w;
 }e[];
 int n,m,f[],g[];
 int read(){
     int t=,f=;char ch=getchar();
     while (ch<''||ch>''){if (ch=='-') f=-;ch=getchar();}
     while (''<=ch&&ch<=''){t=t*+ch-'';ch=getchar();}
     return t*f;
 }
 bool cmp(edge a,edge b){
     return a.w<b.w;
 }
 int main(){
     n=read();m=read();
     for (int i=;i<=m;i++){
         e[i].u=read();e[i].v=read();e[i].w=read();
     }
     std::sort(e+,e++m,cmp);
     int t=,ans=;
     for (int i=;i<=m;i++){
         f[i]=g[e[i].u]+;
         if (e[i].w!=e[i+].w){
             for (int j=t;j<=i;j++)
              g[e[j].v]=std::max(g[e[j].v],f[j]);
             t=i+;
         }
         ans=std::max(ans,f[i]);
     }
     printf("%d\n",ans);
     return ;
 }