SCU 4439 vertex cover (minimum coverage of a bipartite graph)

Question: at least one endpoint of each side needs to be colored. If you want to paint at least a few points

Idea: minimum vertex coverage: associate each edge with at least one of the vertices with the least vertex. This is obviously the minimum vertex coverage problem of the bare path;

Reference: Bipartite Graph

Code:

#include<iostream>#include<algorithm>#include<cstdio>#include<stdio.h>#include<string.h>#include<queue>#include<cmath>#include<map>#include<set>#include<vector>using namespace std;typedef unsigned long long ull;const int maxn = 500 + 10;const ull seed = 131;struct Edge{    int v, next;}edge[maxn * maxn * 2];int head[maxn], match[maxn], vis[maxn], tot;void addEdge(int u, int v){    edge[tot].v = v;    edge[tot].next = head[u];    head[u] = tot++;}bool dfs(int u){    for(int i = head[u]; i != -1; i = edge[i].next){        int v = edge[i].v;        if(!vis[v]){            vis[v] = 1;            if(match[v] == -1 || dfs(match[v])){                match[v] = u;                match[u] = v;                return true;            }        }    }    return false;}int solve(int n){    int ans = 0;    memset(match, -1, sizeof(match));    for(int i = 1; i <= n; i++){        if(match[i] == -1){            memset(vis, 0, sizeof(vis));            if(dfs(i)) ans++;        }    }    return ans;}int main(){    int n, m;    while(~scanf("%d%d", &n, &m)){        memset(head, -1, sizeof(head));        tot = 0;        for(int i = 1; i <= m; i++){            int u, v;            scanf("%d%d", &u, &v);            addEdge(u, v);            addEdge(v, u);        }        printf("%d\n", solve(n));    }    return 0;}

 

SCU 4439 vertex cover (minimum coverage of a bipartite graph)