并查集 示例 ： poj 1703 [Find them, Catch them - 帮派之争]

#include <iostream>#include <string>#include <cstring>#include <cstdlib>#include <cstdio>#include <cmath>#include <vector>#include <stack>#include <deque>#include <queue>#include <bitset>#include <list>#include <map>#include <set>#include <iterator>#include <algorithm>#include <functional>#include <utility>#include <sstream>#include <climits>#include <cassert>#define MID(x,y) ( ( x + y ) >> 1 )#define L(x) ( x << 1 )#define R(x) ( x << 1 | 1 )#define BUG puts("here!!!");#define STOP system("pause");using namespace std;const int N = 100005;int f[N+N];int n, m;int find(int x) {if(f[x] < 0) return x;return f[x] = find(f[x]);}int main() {int loop;cin >> loop;while(loop--) {scanf("%d%d", &n, &m);memset(f, 255, sizeof(f));while(m--) {int a, b;char s[3];scanf("%s%d%d", s, &a, &b);if(s[0] == 'A') {if(find(a) != find(b) && find(a) != find(b+n)) {printf("Not sure yet.\n");}else if(find(a) == find(b)) {printf("In the same gang.\n");}else printf("In different gangs.\n");}else {if(find(a) != find(b+n)) {f[find(a)] = find(b+n);f[find(b)] = find(a+n);}}}}return 0;}

Sample Input
1
5 5
A 1 2
D 1 2
A 1 2
D 2 4
A 1 4
Sample Output
Not sure yet.
In different gangs.
In the same gang.