URAL1291. Gear-wheels

１２９１

不知道为嘛被分在ＤＰ里了　瞎写　注意没被别的轮带动的情况　初始为０　　分母为１

 1 #include <iostream>

 2 #include<cstdio>

 3 #include<cstring>

 4 #include<algorithm>

 5 #include<stdlib.h>

 6 #include<vector>

 7 #include<queue>

 8 using namespace std;

 9 #define N 1010

10 vector<int>ge[N];

11 int co[N],d[N],vis[N];

12 struct node

13 {

14     int f,nu,de;

15 }p[N];

16 int gcd(int a,int b)

17 {

18     return b==0?a:gcd(b,a%b);

19 }

20 void init(int x,int y)

21 {

22     int n1 = co[x]*p[x].nu,n2 = co[y]*p[x].de;

23     if(n1==0||n2==0) n2=1;

24     else

25     {

26         int k = gcd(n1,n2);

27         n1 = n1/k;n2 = n2/k;

28     }

29     if(d[y]==1)

30     p[y].f = 1;

31     else

32     p[y].f = -1;

33     p[y].nu = n1;

34     p[y].de = n2;

35 }

36 void bfs(int u)

37 {

38     queue<int>q;

39     q.push(u);

40     while(!q.empty())

41     {

42         int tu = q.front();

43         q.pop();

44         for(int i = 0 ; i < (int)ge[tu].size() ; i++)

45         {

46             int v = ge[tu][i];

47             if(!vis[v])

48             {

49                 vis[v] = 1;

50                 d[v] = -d[tu];

51                 init(tu,v);

52                 q.push(v);

53             }

54         }

55     }

56 }

57 int main()

58 {

59     int i,n,s,v;

60     scanf("%d",&n);

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

62     {

63         scanf("%d",&co[i]);

64         int a;

65         while(scanf("%d",&a)&&a)

66         ge[i].push_back(a);

67     }

68     scanf("%d%d",&s,&v);

69     d[s] = 1;

70     p[s].f = 1;

71     p[s].nu = v;

72     p[s].de = 1;

73     vis[s] = 1;

74     bfs(s);

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

76     {

77         if(p[i].f==-1&&p[i].nu)

78         printf("-");

79         if(p[i].nu==0)

80         p[i].de = 1;

81         printf("%d/%d\n",p[i].nu,p[i].de);

82     }

83     return 0;

84 }

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