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| #include <iostream>
#include <cstdio>
#include <queue>
#include <climits>
#define INF INT_MAX
using namespace std;
const int N = 610, M = 8e4 + 10;
bool vis[N];
int n, m, st, ed, d[N], pre[N], incf[N];
int idx = -1, hd[N], nxt[M], edg[M], wt[M], f[M];
bool spfa()
{
for (int i = st; i <= ed; i++)
incf[i] = 0;
for (int i = st; i <= ed; i++)
d[i] = INF;
incf[st] = INF;
d[st] = 0;
queue <int> q;
q.push(st);
vis[st] = true;
while (!q.empty())
{
int t = q.front();
q.pop();
vis[t] = false;
for (int i = hd[t]; ~i; i = nxt[i])
if (d[t] + f[i] < d[edg[i]] && wt[i])
{
d[edg[i]] = d[t] + f[i];
pre[edg[i]] = i;
incf[edg[i]] = min(wt[i], incf[t]);
if (!vis[edg[i]])
{
vis[edg[i]] = true;
q.push(edg[i]);
}
}
}
return incf[ed] > 0;
}
int ek()
{
int res = 0;
while (spfa())
{
int t = incf[ed];
res += t * d[ed];
for (int i = ed; i != st; i = edg[pre[i] ^ 1])
{
wt[pre[i]] -= t;
wt[pre[i] ^ 1] += t;
}
}
return res;
}
void add(int a, int b, int c, int d)
{
nxt[++idx] = hd[a];
hd[a] = idx;
edg[idx] = b;
wt[idx] = c;
f[idx] = d;
}
int main()
{
cin >> m >> n;
st = 0;
ed = n + n * m + 1;
for (int i = st; i <= ed; i++)
hd[i] = -1;
for (int i = 1; i <= n; i++)
{
add(st, i, 1, 0);
add(i, st, 0, 0);
}
for (int i = 1, a; i <= n; i++)
for (int j = 1; j <= m; j++)
{
cin >> a;
for (int k = 1; k <= n; k++)
{
add(i, n + (j - 1) * n + k, 1, k * a);
add(n + (j - 1) * n + k, i, 0, - k * a);
}
}
for (int i = 1; i <= m; i++)
for (int j = 1; j <= n; j++)
{
add(n + (i - 1) * n + j, ed, 1, 0);
add(ed, n + (i - 1) * n + j, 0, 0);
}
printf("%.2lf", (double)ek() / (double)n);
return 0;
}
|