POJ 3259 wormholes

POJ 3259 wormholes[★★☆☆☆] graph theory Shortest way bellman

• Main topic:

  The essence is to find out whether the graph has a negative ring. That is, how to find out whether a graph contains a negative ring.
  It is important to note that the path in the input is bidirectional and wormhole is one-way

• Sample Example

  Input:
  2
  3 3 1
  1 2 2
  1 3 4
  2 3 1
  3 1 3
  3 2 1
  1 2 3
  2 3 4
  3 1 8

  Output:
  NO
  YES

• Problem Solving Ideas:

  This problem is good, my optimization of a condition led to WA, or too young.
  But I feel this problem is wrong ... Oh, my God--
  There is my code at the end of the set of samples, a lot of online code is wrong, but to turn to AC, fans.

• Code

#include <iostream>#include <algorithm>using namespace STD;typedef Long LongllConst intINF =1e18+7;intN, M, W;structEdge {intStart, end; ll time;}; Edge e[5500];intCte;ll d[ -];BOOLBellmanints) {if(D[s]! = INF)return 0;//Optimization     for(inti =1; I <= N;    i++) {D[i] = INF; } D[s] =0;intI for(i =1; I <= N; i++) {BOOLUpdate =0; for(intj =0; J < CTE; J + +) {Edge e = e[j];if(D[e.start]! = INF && d[e.end] > D[e.start] + e.time) {D[e.end] = D[e.start] + e.time;//if (D[e.end] < 0) return 1; The wrong optimization. Update =1; }        }if(!update) Break; } for(intj =0; J < CTE; J + +) {Edge e = e[j];if(D[e.start]! = INF && d[e.end] > D[e.start] + e.time) {return 1; }    }//if (i = = n+1) return 1;    return 0;}intMain () {intFCin>> F; while(f--) {CTE =0;Cin>> N >> M >> W; for(inti =1; I <= N;        i++) {D[i] = INF; } for(inti =0; i < M; i++) {intS, E, t;Cin>> s >> e >> t;            Edge Te; Te.start = s; Te.end = e;            Te.time = t;            e[cte++] = te; Te.start = e;            Te.end = s;        e[cte++] = te; } for(inti =0; i < W; i++) {intS, E, t;Cin>> s >> e >> t;            Edge Te; Te.start = s; Te.end = e;            Te.time =-T;        e[cte++] = te; }BOOLFL =0; for(inti =1; I <= N; i++) {fl = Bellman (i);if(FL) Break; }//FL = Bellman (1);        if(FL)cout<<"yes\n";Else cout<<"no\n"; }return 0;}/*15 3 3 103 4 104 5 3 21*/

POJ 3259 wormholes