poj1703 Find them, Catch them（并查集）

Posted 2020-11-03 Surprisez

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。

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<queue>
 4 #include<cstring>
 5 #include<algorithm>
 6 #include<cmath>
 7 #include<stack>
 8 #define lson l, m, rt<<1
 9 #define rson m+1, r, rt<<1|1
10 #define INF 0x3f3f3f3f
11 typedef unsigned long long ll;
12 using namespace std;
13 const int N=100000;
14 int t, n, m, x, y, pre[200010];
15 char c;
16 int find(int x)
17 {
18     while(x != pre[x]){
19         x = pre[x];
20     }
21     return x;
22 }
23 int is_same(int a, int b)
24 {
25     int tx = find(a);
26     pre[a] = tx;
27     int ty = find(b);
28     pre[b] = ty;
29     if(tx == ty) return 1;
30     return 0;
31 }
32 void join(int a, int b)
33 {
34     int tx = find(a);
35     pre[a] = tx;
36     int ty = find(b);
37     pre[b] = ty;
38     pre[tx] = ty;
39 }
40 int main()
41 {
42     scanf("%d", &t);
43     while(t--){
44         scanf("%d%d", &n, &m);
45         for(int i = 1; i <= N*2; i++){
46             pre[i] = i;
47         }
48         //c = getchar();
49         for(int i = 0; i < m; i++){
50             c = getchar();
51             scanf("%c%d%d", &c, &x, &y);
52             if(c == ‘A‘){
53                 if(is_same(x, y)||is_same(x+N, y+N)){
54                     printf("In the same gang.\n");    
55                 }
56                 else{
57                     if(!is_same(x, y)&&!is_same(x, y+N)){
58                         printf("Not sure yet.\n");
59                     }
60                     else printf("In different gangs.\n");
61                 } 
62             }
63             else{
64                 join(x, y+N);
65                 join(x+N, y);
66             }
67         }
68     }
69     return 0;
70 }