poj1703 Find them, Catch them（并查集）

https://vjudge.net/problem/POJ-1703

9ms多，卡着时间过了。上次一道并查集也是这样，总觉得要学一波并查集的优化。。

续：好像是可以只做一层存放敌人即可。

 #include<iostream>
 #include<cstdio>
 #include<queue>
 #include<cstring>
 #include<algorithm>
 #include<cmath>
 #include<stack>
 #define lson l, m, rt<<1
 #define rson m+1, r, rt<<1|1
 #define INF 0x3f3f3f3f
 typedef unsigned long long ll;
 using namespace std;
 const int N=;
 int t, n, m, x, y, pre[];
 char c;
 int find(int x)
 {
     while(x != pre[x]){
         x = pre[x];
     }
     return x;
 }
 int is_same(int a, int b)
 {
     int tx = find(a);
     pre[a] = tx;
     int ty = find(b);
     pre[b] = ty;
     if(tx == ty) return ;
     return ;
 }
 void join(int a, int b)
 {
     int tx = find(a);
     pre[a] = tx;
     int ty = find(b);
     pre[b] = ty;
     pre[tx] = ty;
 }
 int main()
 {
     scanf("%d", &t);
     while(t--){
         scanf("%d%d", &n, &m);
         for(int i = ; i <= N*; i++){
             pre[i] = i;
         }
         //c = getchar();
         for(int i = ; i < m; i++){
             c = getchar();
             scanf("%c%d%d", &c, &x, &y);
             if(c == 'A'){
                 if(is_same(x, y)||is_same(x+N, y+N)){
                     printf("In the same gang.\n");
                 }
                 else{
                     if(!is_same(x, y)&&!is_same(x, y+N)){
                         printf("Not sure yet.\n");
                     }
                     else printf("In different gangs.\n");
                 }
             }
             else{
                 join(x, y+N);
                 join(x+N, y);
             }
         }
     }
     return ;
 }