POJ.1793 Find them, Catch them

1.Problem
http://poj.org/problem?id=1703

2.Idea
Using Union-Find set.

3.Source

 int Parent[200005];  
 int Size[200005];  
 int n, m;  
 void make_set(int v) {  
      Parent[v] = v;  
      Size[v] = 1;  
 }  
 int find_set(int v) {  
      if (v == Parent[v])  
           return v;  
      return Parent[v] = find_set(Parent[v]);  
 }  
 void union_sets(int a, int b) {  
      a = find_set(a);  
      b = find_set(b);  
      if (a != b) {  
           if (Size[a] < Size[b])  
                swap(a, b);  
           Parent[b] = a;  
           Size[a] += Size[b];  
      }  
 }  
 int main()  
 {  
      int t;  
      cin >> t;  
      while (t--) {  
           cin >> n >> m;  
           for (int i = 1; i <= 2 * n; i++) make_set(i);  
           char c;  
           int a, b;  
           for (int i = 0; i < m; i++) {  
                scanf(" %c %d %d", &c, &a, &b);  
                //cin >> c >> a >> b;  
                if (c == 'D') {  
                     union_sets(a, b + n);  
                     union_sets(b, a + n);  
                }  
                else {  
                     if (find_set(a) == find_set(b) || find_set(a + n) == find_set(b + n)) {  
                          puts("In the same gang.");  
                     }  
                     else if (find_set(a) == find_set(b + n) || find_set(a + n) == find_set(b)) {  
                          puts("In different gangs.");  
                     }  
                     else {  
                          puts("Not sure yet.");  
                     }  
                }  
           }  
      }  
      return 0;  
 }