Gym100923H Por Costel and the Match

题目链接：http://codeforces.com/gym/100923/problem/H

分析：并查集，用enemy储存x的敌人，用weight储存权重决定根节点

需用scanf和puts输入输出否则会爆

 1 #include<iostream>
 2 #include<sstream>
 3 #include<cstdio>
 4 #include<cstdlib>
 5 #include<string>
 6 #include<cstring>
 7 #include<algorithm>
 8 #include<functional>
 9 #include<iomanip>
10 #include<numeric>
11 #include<cmath>
12 #include<queue>
13 #include<vector>
14 #include<set>
15 #include<cctype>
16 #define PI acos(-1.0)
17 const int INF = 0x3f3f3f3f;
18 const int NINF = -INF - 1;
19 const int maxn = 1e5 + 5;
20 typedef long long ll;
21 using namespace std;
22 int n, m;
23 int fa[maxn], enemy[maxn], weight[maxn];
24 int find(int x)
25 {
26     return x == fa[x] ? x : fa[x] = find(fa[x]);
27 }
28 void unite(int x, int y)
29 {
30     if (weight[x] < weight[y]) fa[x] = y;
31     else
32     {
33         fa[y] = x;
34         if (weight[x] == weight[y]) weight[x]++;
35     }
36 }
37 int main()
38 {
39     //std::ios::sync_with_stdio(false);
40     freopen("meciul.in", "r", stdin);
41     freopen("meciul.out", "w", stdout);
42     int T;
43     scanf("%d", &T);
44     while (T--)
45     {
46         scanf("%d%d", &n, &m);
47         memset(enemy, 0, sizeof(enemy));
48         memset(weight, 0, sizeof(weight));
49         for (int i = 1; i <= n; ++i) fa[i] = i;
50         while (m--)
51         {
52             int x, y;
53             scanf("%d%d", &x, &y);
54             int f1 = find(x), f2 = find(y);
55             if (f1 == f2) puts("NO");
56             else
57             {
58                 if (!enemy[x]) enemy[x] = y;
59                 else unite(f2, find(enemy[x]));
60                 if (!enemy[y]) enemy[y] = x;
61                 else unite(f1, find(enemy[y]));
62                 puts("YES");
63             }
64         }
65     }
66     return 0;
67 }