mirror of
https://git.sb/baoshuo/OI-codes.git
synced 2024-12-13 04:06:26 +00:00
114 lines
2.4 KiB
C++
114 lines
2.4 KiB
C++
#include <iostream>
|
|
#include <cstring>
|
|
#include <limits>
|
|
#include <queue>
|
|
|
|
using std::cin;
|
|
using std::cout;
|
|
const char endl = '\n';
|
|
|
|
const int N = 1005,
|
|
M = 100005;
|
|
const int to[4][2] = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
|
|
|
|
int n, u, s, t, flow, ans, sum;
|
|
|
|
// Graph
|
|
int idx, head[N], edge[M << 1], ver[M << 1], next[M << 1];
|
|
|
|
void add(int u, int v, int w) {
|
|
next[idx] = head[u];
|
|
ver[idx] = v;
|
|
edge[idx] = w;
|
|
head[u] = idx++;
|
|
}
|
|
|
|
// Dinic
|
|
int d[N], cur[N];
|
|
|
|
bool bfs() {
|
|
memset(d, 0x00, sizeof(d));
|
|
std::queue<int> q;
|
|
d[s] = 1;
|
|
q.push(s);
|
|
cur[s] = head[s];
|
|
|
|
while (!q.empty()) {
|
|
int u = q.front();
|
|
q.pop();
|
|
|
|
for (int i = head[u]; ~i; i = next[i]) {
|
|
int v = ver[i],
|
|
w = edge[i];
|
|
if (w && !d[v]) {
|
|
d[v] = d[u] + 1;
|
|
cur[v] = head[v];
|
|
if (v == t) return true;
|
|
q.push(v);
|
|
}
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
int dinic(int u, int limit) {
|
|
if (u == t) return limit;
|
|
|
|
int flow = 0;
|
|
for (int &i = cur[u]; ~i && flow < limit; i = next[i]) {
|
|
int v = ver[i],
|
|
w = edge[i];
|
|
if (w && d[v] == d[u] + 1) {
|
|
int k = dinic(v, std::min(limit - flow, w));
|
|
if (!k) d[v] = 0;
|
|
edge[i] -= k;
|
|
edge[i ^ 1] += k;
|
|
flow += k;
|
|
}
|
|
}
|
|
|
|
return flow;
|
|
}
|
|
|
|
int main() {
|
|
std::ios::sync_with_stdio(false);
|
|
|
|
memset(head, 0xff, sizeof(head));
|
|
|
|
cin >> n;
|
|
s = 0, t = n * n + 1;
|
|
|
|
for (int i = 1; i <= n; i++) {
|
|
for (int j = 1; j <= n; j++) {
|
|
int w, u = (i - 1) * n + j;
|
|
cin >> w;
|
|
sum += w;
|
|
|
|
if ((i + j) & 1) {
|
|
add(s, u, w);
|
|
add(u, s, 0);
|
|
|
|
for (int k = 0; k < 4; k++) {
|
|
int xx = i + to[k][0],
|
|
yy = j + to[k][1];
|
|
if (1 <= xx && xx <= n && 1 <= yy && yy <= n) {
|
|
int v = (xx - 1) * n + yy;
|
|
add(u, v, std::numeric_limits<int>::max());
|
|
add(v, u, 0);
|
|
}
|
|
}
|
|
} else {
|
|
add(u, t, w);
|
|
add(t, u, 0);
|
|
}
|
|
}
|
|
}
|
|
|
|
while (bfs()) {
|
|
while (flow = dinic(s, std::numeric_limits<int>::max())) ans += flow;
|
|
}
|
|
|
|
cout << sum - ans << endl;
|
|
return 0;
|
|
}
|