HDU ACM 1272 小希的迷宫(并查集)

http://acm.hdu.edu.cn/showproblem.php?pid=1272

题目要求有两个条件:1.在给定图中无环

　　　　　　　　　 2.给定的图有且仅有有1个连通分支

判断环:在输入时判断点a点b是否有相同的根节点,有相同根节点再加一条直接连通的边就有环.

判断连通分支数:判断有几个跟节点 if(father[i]==i)

View Code 
  1 #include <iostream>
  2 using namespace std;
  3 const int MAX = 100000 + 100;
  4 int father[MAX];
  5 int rank1[MAX];
  6 int sign[MAX];
  7 void Make_Set(int x)//初始化
  8 {
  9     father[x] = x;
 10     rank1[x] = 0;
 11 }
 12 
 13 int Find_Set(int x)//找根节点
 14 {
 15     int i=0;
 16     while(father[x] != x)
 17     {
 18         sign[i++] = x;
 19         x = father[x];
 20     }
 21     for(i;i>=1;i--)
 22     {
 23         father[sign[i-1]] = x;
 24     }
 25     return x;
 26 }
 27 
 28 
 29 void Union(int x,int y)//合并
 30 {
 31     x = Find_Set(x);
 32     y = Find_Set(y);
 33     if(x == y)
 34     {
 35         return;
 36     }
 37     if(rank1[x] > rank1[y])
 38     {
 39         father[y] = x;
 40     }
 41     else if(rank1[x] < rank1[y])
 42     {
 43         father[x] = y;
 44     }
 45     else if(rank1[x] ==rank1[y]) 
 46     {
 47         father[x] = y;           
 48         rank1[y]++;             
 49     }
 50 }
 51 
 52 int main()
 53 {
 54     while(1)
 55     {
 56         int i;
 57         int mark = 0;
 58         int used[MAX]={0};
 59         for(i=1;i<=MAX-1;i++)
 60         {
 61             Make_Set(i);
 62         }
 63         for(i=1;i<=MAX-1;i++)
 64         {
 65             int a,b;
 66             cin>>a>>b;
 67             if(a + b == 0)
 68             {
 69                 break;
 70             }
 71             if(a == -1 && b == -1)
 72             {
 73                 return 0;
 74             }
 75             used[a] = 1;
 76             used[b] = 1;
 77             int ra = Find_Set(a);
 78             int rb = Find_Set(b);
 79             if(ra == rb)
 80             {
 81                 mark = 1;
 82             }
 83             Union(a,b);
 84         }
 85         int sum=0;
 86         for(i=1;i<=MAX-1;i++)
 87         {
 88             if(father[i]==i && used[i] == 1)
 89             {
 90                 sum++;
 91             }
 92         }
 93         if(sum > 1 || mark == 1)
 94         {
 95             cout<<"No"<<endl;
 96         }
 97         else
 98         {
 99             cout<<"Yes"<<endl;
100         }
101 
102     }
103     return 0;
104 }

 

posted @ 2012-08-25 17:53  zx雄  阅读(226)  评论(0)  编辑  收藏  举报