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ZOJ 1324 Reactor Cooling——无源汇有上下界的可行流

妖妖妈 2022-08-17 阅读 48


#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
using namespace std;
const int maxn = 410;
const int INF = 0x3f3f3f3f;
int a[maxn], down[maxn*maxn];
struct Edge {
int from, to, flow, cap;
Edge(int a, int b, int c, int d) : from(a), to(b), flow(c), cap(d) {}
};
struct Dinic {
bool vis[maxn];
int n, m, s, t, d[maxn], cur[maxn];
vector<Edge> edges;
vector<int> G[maxn];
void init(int nn) {
n = nn;
edges.clear();
for (int i = 0; i <= n + 5; i++) G[i].clear();
}
void addedge(int from, int to, int flow, int cap) {
edges.push_back(Edge(from, to, flow, cap));
edges.push_back(Edge(to, from, -flow, 0));
m = edges.size();
G[from].push_back(m-2);
G[to].push_back(m-1);
}
bool bfs() {
memset(vis, 0, sizeof(vis));
queue<int> Q; Q.push(s);
d[s] = 0;
vis[s] = 1;
while (!Q.empty()) {
int x = Q.front(); Q.pop();
for (int i = 0; i < G[x].size(); i++) {
Edge &e = edges[G[x][i]];
if (!vis[e.to] && e.cap > e.flow) {
vis[e.to] = 1;
d[e.to] = d[x] + 1;
Q.push(e.to);
}
}
}
return vis[t];
}
int dfs(int x, int a) {
if (x == t || a == 0) return a;
int flow = 0, f;
for (int &i = cur[x]; i < G[x].size(); i++) {
Edge &e = edges[G[x][i]];
if (d[x] + 1 == d[e.to] && (f=dfs(e.to, min(a, e.cap - e.flow))) > 0) {
e.flow += f;
edges[G[x][i]^1].flow -= f;
flow += f;
a -= f;
if (a == 0) break;
}
}
return flow;
}
int maxflow(int ss, int tt) {
s = ss, t = tt;
int flow = 0;
while (bfs()) {
memset(cur, 0, sizeof(cur));
flow += dfs(s, INF);
}
return flow;
}
void output(int m) {
for (int i = 1; i <= m; i++) {
printf("%d\n", down[i] + edges[(i-1)*2].flow);
}
}
}dinic;
int main() {
int T, n, m, from, to, up;
scanf("%d", &T);
for (int kase = 1; kase <= T; kase++) {
scanf("%d %d", &n, &m);
dinic.init(n);
memset(a, 0, sizeof(a));
for (int i = 1; i <= m; i++) {
scanf("%d %d %d %d", &from, &to, &down[i], &up);
dinic.addedge(from, to, 0, up - down[i]);
a[from] -= down[i];
a[to] += down[i];
}
int ss = n + 1, tt = n + 2, sum = 0;
for (int i = 1; i <= n; i++) {
if (a[i] > 0) {
dinic.addedge(ss, i, 0, a[i]);
}
else {
sum -= a[i];
dinic.addedge(i, tt, 0, -a[i]);
}
}
if (kase != 1) printf("\n");
int temp = dinic.maxflow(ss, tt);
if (temp != sum) {
printf("NO\n");
}
else {
printf("YES\n");
dinic.output(m);
}
}
return 0;
}


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