HDU Destroy Transportation system(有上下界的可行流)

#pragma warning(disable:4996)
#include <iostream>
#include <cstring>
#include <string>
#include <vector>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map>
using namespace std;

#define maxn 500
#define maxe 40000
#define inf 0x3f3f3f3f

struct Edge
{
int u, v, cap;
int nxt;
}edge[maxe];

int head[maxn];

struct Dicnic
{
int level[maxn];
int iter[maxn];
int add;
void init(){
add = 0; memset(head, -1, sizeof(head));
memset(iter, -1, sizeof(iter));
}
void insert(int u, int v, int c){
edge[add].u = u; edge[add].v = v; edge[add].cap = c;
edge[add].nxt = head[u]; head[u] = add++;
edge[add].u = v; edge[add].v = u; edge[add].cap = 0;
edge[add].nxt = head[v]; head[v] = add++;
}
void bfs(int s){
memset(level, -1, sizeof(level));
queue<int> que;
level[s] = 0;
que.push(s);
while (!que.empty()){
int v = que.front(); que.pop();
for (int i = head[v]; i != -1; i = edge[i].nxt){
Edge &e = edge[i];
if (e.cap > 0 && level[e.v] < 0){
level[e.v] = level[v] + 1;
que.push(e.v);
}
}
}
}

int dfs(int v, int t, int f){
if (v == t) return f;
for (int &i = iter[v]; i != -1; i = edge[i].nxt){
Edge &e = edge[i]; Edge &reve = edge[i ^ 1];
if (e.cap > 0 && level[v] < level[e.v]){
int d = dfs(e.v, t, min(f, e.cap));
if (d>0){
e.cap -= d; reve.cap += d;
return d;
}
}
}
return 0;
}

int max_flow(int s, int t){
int flow = 0;
for (;;){
bfs(s);
if (level[t] < 0) return flow;
memcpy(iter, head, sizeof(iter));
int f;
while ((f = dfs(s, t, inf))>0){
flow += f;
}
}
}
}net;

int n, m;

int main()
{
int T; cin >> T; int ca = 0;
while (T--){
scanf("%d%d", &n, &m);
net.init();
int ui, vi, di, bi;
int ss = n + 1, tt = ss + 1;
int minflow = 0;
for (int i = 0; i < m; ++i){
scanf("%d%d%d%d", &ui, &vi, &di, &bi);
minflow += di;
net.insert(ui, vi, bi);
net.insert(ss, vi, di);
net.insert(ui, tt, di);
}
if (net.max_flow(ss, tt) == minflow) printf("Case #%d: happy\n", ++ca);
else printf("Case #%d: unhappy\n", ++ca);
}
return 0;
}