ZOJ 2314 Reactor Cooling [无源汇上下界网络流]
2017-03-27 23:31
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#include <iostream> #include <cstdio> #include <cstring> #include <algorithm> using namespace std; typedef long long ll; const int N=205, M=5e5+5, INF=1e9; inline ll read(){ char c=getchar();ll x=0,f=1; while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();} while(c>='0'&&c<='9'){x=x*10+c-'0';c=getchar();} return x*f; } int n, m, u, v, c, b, s, t; int extra ; struct edge{int v, c, f, ne, lower;}e[M]; int cnt=1, h ; inline void ins(int u, int v, int c, int b=0) { //printf("ins %d %d %d\n",u,v,c); e[++cnt]=(edge){v, c, 0, h[u], b}; h[u]=cnt; e[++cnt]=(edge){u, 0, 0, h[v], b}; h[v]=cnt; } int q , head, tail, d , vis , cur ; bool bfs() { memset(vis, 0, sizeof(vis)); head=tail=1; q[tail++]=s; d[s]=0; vis[s]=1; while(head!=tail) { int u=q[head++]; for(int i=h[u];i;i=e[i].ne) if(!vis[e[i].v] && e[i].c > e[i].f) { vis[e[i].v]=1; d[e[i].v]=d[u]+1; q[tail++]=e[i].v; if(e[i].v == t) return true; } } return false; } int dfs(int u, int a) { if(u==t || a==0) return a; int flow=0, f; for(int &i=cur[u];i;i=e[i].ne) if(d[e[i].v] == d[u]+1 && (f=dfs(e[i].v, min(e[i].c-e[i].f, a))) >0) { flow += f; e[i].f += f; e[i^1].f -= f; a -= f; if(a==0) break; } if(a) d[u]=-1; return flow; } int dinic() { int flow=0; while(bfs()) { for(int i=s; i<=t; i++) cur[i]=h[i]; flow+=dfs(s, INF); } return flow; } int main() { freopen("in","r",stdin); int T=read(); while(T--) { n=read(); m=read(); s=0; t=n+1; cnt=1; memset(h,0,sizeof(h)); memset(extra, 0, sizeof(extra)); for(int i=1; i<=m; i++) u=read(), v=read(), b=read(), c=read(), ins(u, v, c-b, b), extra[u]-=b, extra[v]+=b; int sum=0; for(int i=1; i<=n; i++) { if(extra[i]>0) ins(s, i, extra[i]), sum+=extra[i]; else ins(i, t, -extra[i]); } int flow=dinic(); //printf("flow %d %d\n",flow,sum); if(flow!=sum) puts("NO"); else { puts("YES"); for(int i=1; i<=m; i++) printf("%d\n",e[i<<1].f + e[i<<1].lower); } } }
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