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OI-codes/AcWing/2188/2188.cpp

119 lines
2.3 KiB
C++

#include <iostream>
#include <cstring>
#include <limits>
#include <queue>
using std::cin;
using std::cout;
const char endl = '\n';
const int N = 205,
M = 10205;
int n, m, s, t;
int idx, head[N], ver[M << 2], next[M << 2];
std::pair<int, int> edge[M << 2];
int f[N], d[N], cur[N];
void add(int u, int v, int a, int b) {
ver[idx] = v;
edge[idx] = std::make_pair(a, b);
next[idx] = head[u];
head[u] = idx++;
}
bool bfs() {
memset(d, 0x00, sizeof(d));
std::queue<int> q;
q.push(s);
d[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];
if (!d[v] && edge[i].first) {
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];
if (d[v] == d[u] + 1 && edge[i].first) {
int k = dinic(v, std::min(edge[i].first, limit - flow));
if (!k) d[v] = 0;
edge[i].first -= k;
edge[i ^ 1].first += k;
flow += k;
}
}
return flow;
}
int main() {
std::ios::sync_with_stdio(false);
cin.tie(nullptr);
memset(head, 0xff, sizeof(head));
cin >> n >> m;
for (int i = 1, u, v, a, b; i <= m; i++) {
cin >> u >> v >> a >> b;
add(u, v, b - a, a);
add(v, u, 0, 0);
f[u] -= a, f[v] += a;
}
int sum = 0;
s = 0, t = n + 1;
for (int i = 1; i <= n; i++) {
if (f[i] > 0) {
add(s, i, f[i], 0);
add(i, s, 0, 0);
sum += f[i];
} else if (f[i] < 0) {
add(i, t, -f[i], 0);
add(t, i, 0, 0);
}
}
int res = 0, flow;
while (bfs()) {
while (flow = dinic(s, std::numeric_limits<int>::max())) res += flow;
}
if (res == sum) {
cout << "YES" << endl;
for (int i = 0; i < m << 1; i += 2) {
cout << edge[i ^ 1].first + edge[i].second << endl;
}
} else {
cout << "NO" << endl;
}
return 0;
}