【HDOJ】1811 Rank of Tetris

并查集+拓扑排序。使用并查集解决a = b的情况。

 #include <iostream>
 #include <cstdio>
 #include <cstring>
 #include <queue>
 using namespace std;

 #define MAXN 10005

 typedef struct ArcNode {
     int adjvex;
     ArcNode *next;
 } ArcNode;

 typedef struct VNode {
     int count;
     ArcNode *first;
 } VNode;

 VNode nodes[MAXN];
 int pre[MAXN], n;
 int srca[MAXN<<],srcb[MAXN<<];
 char op[MAXN<<];
 bool flag;

 int find(int x) {
     int r = x;
     while (r != pre[r])
         r = pre[r];
     return r;
 }

 void merge(int a, int b) {
     int x = find(a);
     int y = find(b);
     pre[x] = y;
 }

 void Insert(int x, int y) {
     ArcNode *p = new ArcNode;
     nodes[y].count++;
     p->adjvex = y;
     p->next = nodes[x].first;
     nodes[x].first = p;
 }

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

     while (scanf("%d %d",&n,&m) != EOF) {
         for (i=; i<n; ++i) {
             nodes[i].count = ;
             nodes[i].first = NULL;
             pre[i] = i;
         }
         for (i=; i<m; ++i) {
             scanf("%d %c %d", &srca[i], &op[i], &srcb[i]);
             if (op[i] == '=')
                 merge(srca[i], srcb[i]);
         }
         flag = false;
         for (i=; i<m; ++i) {
             if (op[i] == '=')
                 continue;
             x = find(srca[i]);
             y = find(srcb[i]);
             if (x == y) {
                 flag = true;
                 break;
             }
             if (op[i] == '>')
                 Insert(x, y);
             else
                 Insert(y, x);
         }
         if (flag) {
             printf("CONFLICT\n");
             continue;
         }
         queue<int> que;
         int index;
         ArcNode *p;
         m = ;
         for (i=; i<n; ++i) {
             if (i==find(i)) {
                 ++m;
                 if (nodes[i].count==)
                     que.push(i);
             }
         }
         while (!que.empty()) {
             if (que.size() > )
                 flag = true;
             index = que.front();
             que.pop();
             p = nodes[index].first;
             --m;
             while (p != NULL) {
                 j = p->adjvex;
                 --nodes[j].count;
                 if (nodes[j].count == )
                     que.push(j);
                 p = p->next;
             }
         }
         if (m)
             printf("CONFLICT\n");
         else if (flag)
             printf("UNCERTAIN\n");
         else
             printf("OK\n");
     }

     return ;
 }