Max match of poj2239 Bipartite Graph

Problem: poj2239

Analysis:

This question shows the course duration for each course. Finding the maximum number of courses can be converted to the maximum matching problem in the bipartite graph.

Set set a as the course set, Set B as the class time set, and create a bipartite graph based on the input. The largest course selection book is the maximum matching number of the Bipartite Graph, which can be solved using the Hungary algorithm.

AC code

 1 //Memory: 252K        Time: 16MS 2 #include <iostream> 3 #include <cstring> 4 #include <cstdio> 5  6 using namespace std; 7  8 const int maxl = 301; 9 const int maxc = 85;10 int edge[maxc][maxl];11 int ne[maxc];12 int match[maxl];13 bool vis[maxl];14 int n, t;15 int a, b;16 17 bool findPath(int start)18 {19     for (int i = 0; i < ne[start]; i++){20         int current = edge[start][i];21         if (vis[current]) continue;22         vis[current] = 1;23         if ( !match[current] || findPath(match[current]) ){24             match[current] = start;25             return true;26         }27     }28     return false;29 }30 31 int solve()32 {33     memset(match, 0, sizeof(match));34     int cnt = 0;35     for (int i = 1; i <= 84; i++) {36         memset(vis, 0, sizeof(vis));37         if (findPath(i)) cnt++;38     }39     return cnt;40 }41 42 void input()43 {44     memset(edge, 0, sizeof(edge));45     memset(ne, 0, sizeof(ne));46     for (int i = 0; i < n; i++){47         scanf("%d", &t);48         while (t--){49             scanf("%d%d", &a, &b);50             int class_num = (a - 1) * 12 + b;51             edge[ class_num ][ ne[class_num]++ ] = i;52         }53     }54 }55 56 int main()57 {58     while ( ~scanf("%d", &n) ){59         input();60         int ans = solve();61         printf("%d\n", ans);62     }63     return 0;64 }