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Maximum LIS on graph edges.cpp
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Maximum LIS on graph edges.cpp
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/// Codeforces 459E - Pashmak and Graph
/// dp problem
/// Nice problem!!
#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
const int maxx=300001;
typedef pair<int,int> pi;
vector<pi>edge[maxx];
int temp_dp[maxx];
int dp[maxx];
int main()
{
ios::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
int n,m,wei,u,v,U,V;
cin>>n>>m;
for(int i=0;i<m;i++)
{
cin>>u>>v>>wei;
edge[wei].push_back(make_pair(u,v));
}
for(int i=0;i<maxx;i++)
{
for(int j=0;j<edge[i].size();j++)
{
U=edge[i][j].first;
V=edge[i][j].second;
temp_dp[V]=max(temp_dp[V],dp[U]+1);
/// printf("temp_dp[%d]=%d ,dp[%d]+1 = %d\n",V,temp_dp[V],U,dp[U]+1);
}
/// store new dp value for vertices
for(int j=0;j<edge[i].size();j++)
{
int V=edge[i][j].second;
dp[V]=max(dp[V],temp_dp[V]);
/// printf("dp[%d]=%d\n",*it,dp[*it]);
}
}
int ans=0;
for(int i=1;i<=n;i++) ans=max(ans,dp[i]);
cout<<ans<<endl;
return 0;
}