Submission #1757940

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Source Code Expand

#include<iostream>
#include<cstdio>
#include<vector>
#include<map>
#include<string>
#include<sstream>
#include<cmath>
#include<climits>
#include<algorithm>
#include<bitset>
#include<set>
#include<stack>
#include<queue>
#include<iomanip>
#include<memory.h>
#include<complex>
using namespace std;  
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef tuple<int,int> tii;
#define rep(i,n) for(ll i=0;i<(n);i++)  
#define pb push_back
#define mt make_tuple
#define ALL(a) (a).begin(),(a).end()
#define FST first
#define SEC second  
const int INF = (INT_MAX/2);
const ll LLINF = (LLONG_MAX/2);
const double eps = 1e-8;
const double PI = M_PI;  
#define DEB cerr<<"!"<<endl
#define SHOW(a,b) cerr<<(a)<<" "<<(b)<<endl
#define SHOWARRAY(ar,i,j) REP(a,i)REP(b,j)cerr<<ar[a][b]<<((b==j-1)?((a==i-1)?("\n\n"):("\n")):(" "))
#define DIV int(1e9+7)
inline ll pow(ll x,ll n,ll m){ll r=1;while(n>0){if((n&1)==1)r=r*x%m;x=x*x%m;n>>=1;}return r%m;}
inline ll lcm(ll d1, ll d2){return d1 / __gcd(d1, d2) * d2;}
 
/* Coding Space*/
struct Edge{
  int from,to,cost;
};
vector<Edge> G;
ll d[1001];
int n,m;
bool BellmanFord(int s){
  rep(i,n) d[i] = LLINF;
  d[s] = 0;
  for(int x = 0;; x++){
    bool update = false;
    rep(i,m){
      Edge e = G[i];
      if(d[e.from] != LLINF && d[e.to] > d[e.from] + e.cost){
        d[e.to] = d[e.from] + e.cost;
        update = true;
      }
    }
    if(!update) break;
    if(x > n)  return true;
  }
  return false;
}
bool find_negative_loop(){
  rep(i,n) d[i] = 0;
  rep(i,n)rep(j,m){
    Edge e = G[j];
    if(d[e.to] > d[e.from] + e.cost){
      d[e.to] = d[e.from] + e.cost;
      if(i == n - 1) return true;
    }
  }
  return false;
}
int main(){
  cin >> n >> m;
  G.resize(m);
  rep(i,m){
    int a,b,c; cin >> a >> b >> c;
    a--,b--;
    G[i] = Edge{a,b,-c};
  }
  if(find_negative_loop()){
    cout << "inf" << endl;
  }else{
    cout << (BellmanFord(0),-d[n-1]) << endl;
  }
}

Submission Info

Judge Result