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=100000;
int t, n, m, x, y, pre[200010];
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 1;
    return 0;
}
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 = 1; i <= N*2; i++){
            pre[i] = i;
        }
        //c = getchar();
        for(int i = 0; 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.
");    
                }
                else{
                    if(!is_same(x, y)&&!is_same(x, y+N)){
                        printf("Not sure yet.
");
                    }
                    else printf("In different gangs.
");
                } 
            }
            else{
                join(x, y+N);
                join(x+N, y);
            }
        }
    }
    return 0;
}