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OI-codes/Luogu/P4001/P4001.cpp

129 lines
2.4 KiB
C++

#include <iostream>
#include <algorithm>
#include <iterator>
#include <queue>
using std::cin;
using std::cout;
const char endl = '\n';
const int N = 1005,
M = N * N;
const int INF = 0x3f3f3f3f;
int n, m, s, t, ans;
int idx, head[M], edge[M << 3], ver[M << 3], next[M << 3];
int dist[M], cur[M];
int id(int x, int y) {
return (x - 1) * 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(dist), std::end(dist), 0);
std::copy(std::begin(head), std::end(head), std::begin(cur));
std::queue<int> q;
q.emplace(s);
dist[s] = 1;
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 && !dist[v]) {
dist[v] = dist[u] + 1;
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 (dist[v] == dist[u] + 1 && w) {
int k = dinic(v, std::min(w, limit - flow));
if (!k) dist[v] = 0;
edge[i] -= k;
edge[i ^ 1] += k;
flow += k;
}
}
return flow;
}
int main() {
std::ios::sync_with_stdio(false);
cin.tie(nullptr);
std::fill(std::begin(head), std::end(head), -1);
cin >> n >> m;
s = id(1, 1), t = id(n, m);
for (int i = 1; i <= n; i++) {
for (int j = 1, x; j < m; j++) {
cin >> x;
add(id(i, j), id(i, j + 1), x);
add(id(i, j + 1), id(i, j),x);
}
}
for (int i = 1; i < n; i++) {
for (int j = 1, x; j <= m; j++) {
cin >> x;
add(id(i, j), id(i + 1, j), x);
add(id(i + 1, j), id(i, j), x);
}
}
for (int i = 1; i < n; i++) {
for (int j = 1, x; j < m; j++) {
cin >> x;
add(id(i, j), id(i + 1, j + 1), x);
add(id(i + 1, j + 1), id(i, j), x);
}
}
while (bfs()) {
while (int flow = dinic(s, INF)) ans += flow;
}
cout << ans << endl;
return 0;
}