解法是匈牙利+二分

但是不知道为什么WA on 7,9,10

希望佬们能指出问题，或给出hack数据

#include <bits/stdc++.h>

using namespace std;

const int Maxn = 20005;

struct edge
{
    int to, nxt;
} e[Maxn << 1];
int tot = -1, head[Maxn];
void add(int u, int v)
{
    e[++tot].to = v;
    e[tot].nxt = head[u];
    head[u] = tot;
}

int n, m, match[Maxn], a[Maxn][Maxn], que[Maxn], k, pos;
bool st[Maxn];

bool find(int u)
{
    for (int i = head[u]; ~i; i = e[i].nxt)
    {
        int v = e[i].to;
        if (st[v])
            continue;
        st[v] = 1;
        if (!match[v] || find(match[v]))
        {
            match[v] = u;
            return true;
        }
    }

    return false;
}

bool check(int x)
{
    int ans = 0;
    tot = -1;
    memset(head, -1, sizeof(head));
    memset(match, 0, sizeof(match));
    for (int i = 1; i <= n; i++)
    {
        for (int j = 1; j <= m; j++)
        {
            if (a[i][j] <= que[x])
                add(i, j);
        }
    }

    for (int i = 1; i <= n; i++)
    {
        memset(st, 0, sizeof(st));
        if (find(i))
            ans++;
    }

    if (ans > n - k)
        return true;
    else
        return false;
}

int main()
{
    cin >> n >> m >> k;
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++)
        {
            cin >> a[i][j];
            que[(i - 1) * m + j] = a[i][j];
        }

    sort(que + 1, que + 1 + n * m);

    int l = 1, r = n * m;
    while (l <= r)
    {
        int mid = (l + r) >> 1;
        if (check(mid))
            pos = que[mid], r = mid - 1;
        else
            l = mid + 1;
    }

    cout << pos;
    return 0;
}