并查集+拓扑排序。使用并查集解决a = b的情况。
1 #include <iostream> 2 #include <cstdio> 3 #include <cstring> 4 #include <queue> 5 using namespace std; 6 7 #define MAXN 10005 8 9 typedef struct ArcNode { 10 int adjvex; 11 ArcNode *next; 12 } ArcNode; 13 14 typedef struct VNode { 15 int count; 16 ArcNode *first; 17 } VNode; 18 19 VNode nodes[MAXN]; 20 int pre[MAXN], n; 21 int srca[MAXN<<1],srcb[MAXN<<1]; 22 char op[MAXN<<1]; 23 bool flag; 24 25 int find(int x) { 26 int r = x; 27 while (r != pre[r]) 28 r = pre[r]; 29 return r; 30 } 31 32 void merge(int a, int b) { 33 int x = find(a); 34 int y = find(b); 35 pre[x] = y; 36 } 37 38 void Insert(int x, int y) { 39 ArcNode *p = new ArcNode; 40 nodes[y].count++; 41 p->adjvex = y; 42 p->next = nodes[x].first; 43 nodes[x].first = p; 44 } 45 46 int main() { 47 int m; 48 int i, j, x, y; 49 50 while (scanf("%d %d",&n,&m) != EOF) { 51 for (i=0; i<n; ++i) { 52 nodes[i].count = 0; 53 nodes[i].first = NULL; 54 pre[i] = i; 55 } 56 for (i=0; i<m; ++i) { 57 scanf("%d %c %d", &srca[i], &op[i], &srcb[i]); 58 if (op[i] == '=') 59 merge(srca[i], srcb[i]); 60 } 61 flag = false; 62 for (i=0; i<m; ++i) { 63 if (op[i] == '=') 64 continue; 65 x = find(srca[i]); 66 y = find(srcb[i]); 67 if (x == y) { 68 flag = true; 69 break; 70 } 71 if (op[i] == '>') 72 Insert(x, y); 73 else 74 Insert(y, x); 75 } 76 if (flag) { 77 printf("CONFLICT "); 78 continue; 79 } 80 queue<int> que; 81 int index; 82 ArcNode *p; 83 m = 0; 84 for (i=0; i<n; ++i) { 85 if (i==find(i)) { 86 ++m; 87 if (nodes[i].count==0) 88 que.push(i); 89 } 90 } 91 while (!que.empty()) { 92 if (que.size() > 1) 93 flag = true; 94 index = que.front(); 95 que.pop(); 96 p = nodes[index].first; 97 --m; 98 while (p != NULL) { 99 j = p->adjvex; 100 --nodes[j].count; 101 if (nodes[j].count == 0) 102 que.push(j); 103 p = p->next; 104 } 105 } 106 if (m) 107 printf("CONFLICT "); 108 else if (flag) 109 printf("UNCERTAIN "); 110 else 111 printf("OK "); 112 } 113 114 return 0; 115 }