某程笔试T2，最小点覆盖

题意：

N*M 01矩阵，每次可以删去一行或者一列，问删去所有的1最少操作次数

emmm

poj3041原题
二分图，行当成一个点放左边，列当成一个点放右边
即求最小点覆盖 == 最大匹配

好久不做题脑子快生锈了

code

好多人吐槽这vector的格式

不知道用自己写的板子算不算作弊

#include<bits/stdc++.h>
using namespace std;
const int N = 1111;

struct Hungary{
    vector <int> G[N];
    bool used[N];
    int girl[N], n, m;

    inline void init(int _n, int _m){
        n = _n, m = _m;
        for (int i = 0; i <= n; i++) G[i].clear();
    }

    inline void addEdge(const int &u, const int &v){
        G[u].push_back(v);
    }

    bool Find(int x){
        for (int i = 0; i < G[x].size(); i++){
            int j = G[x][i];
            if (used[j]) continue;
            used[j] = 1;
            if (girl[j] == -1 || Find(girl[j])) {
                girl[j] = x;
                return true;
            }
        }
        return false;
    }

    inline int hungary(const int &n, const int &m){
        int all = 0;
        memset(girl, -1, sizeof girl);
        for (int i = 0; i < n; i++) {
            memset(used, 0, sizeof(used)); //这个在每一步中清空
            if (Find(i)) all += 1;
        }
        //for (int i = 0; i < m; i++) printf("girl[%d] = %d\n", i, girl[i]);
        //printf("all = %d\n", all);
        return all;
    }
} hg;

int calculate(int rows, int cols, vector < vector < int > > matrix) {
    hg.init(rows, cols);
    for (int i = 0; i < rows; i++){
        for (int j = 0; j < cols; j++){
            if (matrix[i][j]) hg.addEdge(i, j);
        }
    }
    int match = hg.hungary(rows, cols);
    //printf("%d\n", match);
    //int ans = rows + cols - match;
    return match;
}
/******************************结束写代码******************************/

int main() {
    //freopen("in.txt", "r", stdin);
    int res;
    int _matrix_rows = 0;
    int _matrix_cols = 0;
    cin >> _matrix_rows >> _matrix_cols;
    vector< vector < int > > _matrix(_matrix_rows);
    for(int _matrix_i=0; _matrix_i<_matrix_rows; _matrix_i++) {
        for(int _matrix_j=0; _matrix_j<_matrix_cols; _matrix_j++) {
            int _matrix_tmp;
            cin >> _matrix_tmp;
            _matrix[_matrix_i].push_back(_matrix_tmp);
        }
    }

    res = calculate(_matrix_rows, _matrix_cols, _matrix);
    cout << res << endl;
    return 0;
}