poj 1469 COURSES 解题报告

题目链接：http://poj.org/problem?id=1469

题目意思：略

for 循环中遍历的对象要特别注意，究竟是遍历课程数P 还是 学生数N，不要搞混！

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 using namespace std;
 5
 6 const int maxn = 300 + 5;
 7 int match[maxn], map[maxn][maxn];
 8 int vis[maxn];
 9 int P, N, cnt;
10
11 int dfs(int x)
12 {
13     for (int i = 1; i <= N; i++)   // 遍历学生数
14     {
15         if (!vis[i] && map[x][i])
16         {
17             vis[i] = 1;
18             if (match[i] == 0|| dfs(match[i]))
19             {
20                 match[i] = x;
21                 return 1;
22             }
23         }
24     }
25     return 0;
26 }
27
28 void Hungary()
29 {
30     cnt = 0;
31     for (int i = 1; i <= P; i++)  // 遍历课程数
32     {
33         memset(vis, 0, sizeof(vis));
34         cnt += dfs(i);
35     }
36 }
37
38 int main()
39 {
40     int T, num, stu_num;
41     while (scanf("%d", &T) != EOF)
42     {
43         while (T--)
44         {
45             memset(match, 0, sizeof(match));
46             memset(map, 0, sizeof(map));
47
48             scanf("%d%d", &P, &N);
49             for (int i = 1; i <= P; i++)
50             {
51                 scanf("%d", &num);
52                 for (int j = 1; j <= num; j++)
53                 {
54                     scanf("%d", &stu_num);
55                     map[i][stu_num] = 1;
56                 }
57             }
58             Hungary();
59             printf("%s\n", cnt == P ? "YES" : "NO");
60         }
61     }
62     return 0;
63 }

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