poj1860Currency Exchange(bell_fordmoban)

http://poj.org/problem?id=1860

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 1 #include <iostream>

 2 #include<cstdio>

 3 #include<cstring>

 4 #include<algorithm>

 5 #include<stdlib.h>

 6 #include<vector>

 7 #include<queue>

 8 #include<cmath>

 9 using namespace std;

10 #define INF 0xfffffff

11 double dis[110],v;

12 int n,m;

13 struct node

14 {

15     int r,c;

16     double r1,c1,r2,c2;

17 }p[110];

18 int bell_ford(int s)

19 {

20     int i,j;

21     memset(dis,0,sizeof(dis));

22     dis[s] = v;

23     for(i = 1; i <= n ; i++)

24     {

25         int flag = 0;

26         for(j = 1; j <= m ; j++)

27         {

28             if((dis[p[j].r]-p[j].c1)*p[j].r1>dis[p[j].c])

29             dis[p[j].c] = (dis[p[j].r]-p[j].c1)*p[j].r1;

30             if((dis[p[j].c]-p[j].c2)*p[j].r2>dis[p[j].r])

31             dis[p[j].r] = (dis[p[j].c]-p[j].c2)*p[j].r2;

32             flag = 1;

33 

34         }

35         if(!flag) break;

36     }

37     for(j = 1; j <= m ; j++)

38     {

39         if((dis[p[j].r]-p[j].c1)*p[j].r1>dis[p[j].c])

40         return 1;

41         if((dis[p[j].c]-p[j].c2)*p[j].r2>dis[p[j].r])

42         return 1;

43     }

44     return 0;

45 }

46 int main()

47 {

48     int i,s;

49     while(scanf("%d%d%d%lf",&n,&m,&s,&v)!=EOF)

50     {

51         for(i = 1; i <= m ; i++)

52         {

53             scanf("%d%d%lf%lf%lf%lf",&p[i].r,&p[i].c,&p[i].r1,&p[i].c1,&p[i].r2,&p[i].c2);

54         }

55         if(bell_ford(s))

56         {

57             puts("YES");

58         }

59         else

60         puts("NO");

61     }

62     return 0;

63 }

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