POJ1703 Find them, Catch them

 1 /*by SilverN*/
 2 #include<iostream>
 3 #include<algorithm>
 4 #include<cstring>
 5 #include<cstdio>
 6 #include<cmath>
 7 using namespace std;
 8 const int mxn=120000;
 9 int fa[mxn<<1];
10 char c[5];
11 int n,m;
12 int find(int x){
13     if(fa[x]==x)return x;
14     return fa[x]=find(fa[x]);
15 }
16 int main(){
17     int T;
18     int i,j;
19     int x,y;
20     scanf("%d",&T);
21     while(T--){
22         scanf("%d%d",&n,&m);
23         int nn=2*n;
24         for(i=1;i<=nn;i++){
25             fa[i]=i;
26         }
27         for(i=1;i<=m;i++){
28             scanf("%s%d%d",c,&x,&y);
29             if(c[0]==‘D‘){
30                 x=find(x);//
31                 y=find(y);//AC以后试着优化，删了这两条，居然MLE了
32                 //想来是这两步起了压缩并查集路径的作用？ 
33                 int a=find(x+n);
34                 int b=find(y+n);
35                 fa[a]=y;
36                 fa[b]=x;
37                 
38             }
39             else{
40                 if(find(x)==find(y)){
41                     printf("In the same gang.\n");
42                     continue;
43                 }
44                 if(find(x)==find(y+n) || find(y)==find(x+n)){
45                     printf("In different gangs.\n");
46                     continue;
47                 }
48                 printf("Not sure yet.\n");
49             }
50         }
51     }
52     return 0;
53 }