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OI-codes/S2OJ/1810/1810.cpp

168 lines
3.9 KiB
C++

#include <iostream>
#include <algorithm>
#include <iterator>
#include <queue>
using std::cin;
using std::cout;
const char endl = '\n';
const int N = 55 * 55 * 2,
M = N * N;
const int INF = 0x3f3f3f3f;
int n, m, s, t, a[55][55], flow, res, ans;
int idx, head[N], ver[M << 1], edge[M << 1], next[M << 1];
int dis[N], cur[N];
int id(int x, int y, int k) {
return k * n * m + x * m + y;
}
void add(int u, int v, int w) {
next[idx] = head[u];
ver[idx] = v;
edge[idx] = w;
head[u] = idx++;
}
bool bfs() {
std::fill(std::begin(dis), std::end(dis), 0);
std::queue<int> q;
q.emplace(s);
dis[s] = 1;
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 && !dis[v]) {
dis[v] = dis[u] + 1;
cur[v] = head[v];
if (v == t) return true;
q.emplace(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]) {
cur[u] = i;
int v = ver[i],
w = edge[i];
if (w && dis[v] == dis[u] + 1) {
int k = dinic(v, std::min(w, limit - flow));
if (!k) dis[v] = 0;
edge[i] -= k;
edge[i ^ 1] += k;
flow += k;
}
}
return flow;
}
int main() {
std::ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> m;
s = 0, t = id(n, m, 1) + 1;
std::fill(std::begin(head), std::end(head), -1);
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= m; j++) {
cin >> a[i][j];
add(id(i, j, 0), id(i, j, 1), INF);
add(id(i, j, 1), id(i, j, 0), 0);
}
}
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= m; j++) {
int max = 0;
if (a[i][j] == -1) {
add(s, id(i, j, 0), INF);
add(id(i, j, 0), s, 0);
for (int k = i; k >= 1; k--) {
max = std::max(max, a[k][j]);
}
for (int k = i; k > 1; k--) {
add(id(k, j, 0), id(k - 1, j, 0), max - std::max(a[k][j], 0));
add(id(k - 1, j, 0), id(k, j, 0), 0);
}
} else if (a[i][j] == -2) {
add(s, id(i, j, 0), INF);
add(id(i, j, 0), s, 0);
for (int k = i; k <= n; k++) {
max = std::max(max, a[k][j]);
}
for (int k = i; k < n; k++) {
add(id(k, j, 0), id(k + 1, j, 0), max - std::max(a[k][j], 0));
add(id(k + 1, j, 0), id(k, j, 0), 0);
}
} else if (a[i][j] == -3) {
add(id(i, j, 1), t, INF);
add(t, id(i, j, 1), 0);
for (int k = 1; k <= j; k++) {
max = std::max(max, a[i][k]);
}
for (int k = 1; k < j; k++) {
add(id(i, k, 1), id(i, k + 1, 1), max - std::max(a[i][k + 1], 0));
add(id(i, k + 1, 1), id(i, k, 1), 0);
}
} else if (a[i][j] == -4) {
add(id(i, j, 1), t, INF);
add(t, id(i, j, 1), 0);
for (int k = m; k >= j; k--) {
max = std::max(max, a[i][k]);
}
for (int k = m; k > j; k--) {
add(id(i, k, 1), id(i, k - 1, 1), max - std::max(a[i][k - 1], 0));
add(id(i, k - 1, 1), id(i, k, 1), 0);
}
}
ans += max;
}
}
while (bfs()) {
while (flow = dinic(s, INF)) res += flow;
}
cout << ans - res << endl;
return 0;
}