Submission #1280925

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Source Code Expand

#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include<sstream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<climits>
#include<cmath>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<queue>
#include<numeric>
#include<functional>
#include<algorithm>
#include<bitset>
#include<tuple>
#include<unordered_set>
#include<random>
#include<array>
#include<cassert>
using namespace std;
#define INF (1LL<<60)
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define uniq(v) v.erase(unique(all(v)),v.end())


vector<pair<int, int>> edge[1000];


long long d1[1000], d2[1000];


int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);

	int n,m;
	cin>>n>>m;
	rep(i,m){
		int a,b,c;
		cin>>a>>b>>c;
		a--;b--;
		edge[a].emplace_back(b,c);
	}
	rep(i, n)d1[i]=-INF;
	d1[0]=0;
	rep(i,n){
		rep(j,n){
			for (auto e: edge[j]){
				d1[e.first] = max(d1[e.first], d1[j]+e.second);
			}
		}
	}
	memcpy(d2,d1,sizeof(d1));
	rep(i, n){
		rep(j, n){
			for (auto e : edge[j]){
				d2[e.first] = max(d2[e.first], d2[j] + e.second);
			}
		}
	}


	if (d1[n - 1] < d2[n - 1]){
		cout << "inf"<<endl;
	}
	else{
		cout << d1[n-1]<<endl;
	}

	return 0;
}

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