POJ 2492 A Bug's Life(并查集)

题目链接

居然没更新flag就交了，错了两次。。3个题，都是一个类型。

 1 #include <cstring>

 2 #include <cstdio>

 3 #include <string>

 4 #include <iostream>

 5 #include <algorithm>

 6 #include <vector>

 7 using namespace std;

 8 int o[5001];

 9 int flag[5001];

10 int find(int x)

11 {

12     if(x == o[x]) return x;

13     int t = find(o[x]);

14     flag[x] = (flag[x] + flag[o[x]])%2;

15     return o[x] = t;

16 }

17 int main()

18 {

19     int n,m,i,T,cas = 1,x,y,tx,ty,z;

20     scanf("%d",&T);

21     while(cas <= T)

22     {

23         scanf("%d%d",&n,&m);

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

25         {

26             o[i] = i;

27             flag[i] = 0;

28         }

29         z = 1;

30         for(i = 0; i < m; i ++)

31         {

32             scanf("%d%d",&x,&y);

33             if(z)

34             {

35                 tx = find(x);

36                 ty = find(y);

37                 if(tx != ty)

38                 {

39                     o[tx] = ty;

40                     flag[tx] = (flag[y] - flag[x] + 3)%2;

41                 }

42                 else if(tx == ty)

43                 {

44                     if(flag[x] == flag[y])

45                     z = 0;

46                 }

47             }

48         }

49         printf("Scenario #%d:\n",cas++);

50         if(z)

51         printf("No suspicious bugs found!\n");

52         else

53         printf("Suspicious bugs found!\n");

54         if(cas <= T) printf("\n");

55     }

56     return 0;

57 }