【HDOJ】1829 A Bug's Life

并查集变型。题意就是x与y是互斥的，下列是否数据是否可保证x-y是否均为互斥。

 #include <cstdio>
 #include <cstring>

 #define MAXN 2005

 int pre[MAXN];
 int opp[MAXN];
 int n;
 bool flag;

 int find(int x) {
     return pre[x]==x ? x:pre[x]=find(pre[x]);
 }

 void merge(int x, int y) {
     if (!flag) return ;
     x = find(x);
     y = find(y);
     if (x == y) {
         flag = false;
         return;
     }
     if (opp[x]) pre[opp[x]] = y;
     if (opp[y]) pre[opp[y]] = x;
     opp[x] = y;
     opp[y] = x;
 }

 int main() {
     int case_n, m;
     int i, j, x, y;

     scanf("%d", &case_n);

     for (j=; j<=case_n; ++j) {
         scanf("%d %d", &n, &m);
         for (i=; i<=n; ++i)
             pre[i] = i;
         memset(opp, , sizeof(opp));
         flag = true;
         while (m--) {
             scanf("%d %d", &x, &y);
             merge(x, y);
         }
         printf("Scenario #%d:\n", j);
         if (flag)
             printf("No suspicious bugs found!\n\n");
         else
             printf("Suspicious bugs found!\n\n");
     }

     return ;
 }