【网络流】 SGU 194 Reactor Cooling 无源无汇上下界可行流裸题

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ISAP好长啊。。。居然打了20分钟。。。。

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <string>
#include <iostream>
#include <algorithm>
#include <sstream>
#include <cmath>
using namespace std;
#include <queue>
#include <stack>
#include <vector>
#include <deque>
#include <set>
#include <map>
#include <time.h>;
#define cler(arr,val)    memset(arr,val,sizeof(arr))
#define FOR(i,a,b)  for(int i=a;i<=b;i++)
#define IN   freopen ("in.txt","r",stdin);
#define OUT  freopen ("out.txt","w",stdout);
typedef long long  LL;
const int MAXN = 10010;
const int MAXM = 44224;
const int INF = 0x3f3f3f3f;
const int mod = 1000000007;
struct Edge
{
    int to,next,cap,flow;
}edge[MAXM];
int tol,head[MAXN];
int gap[MAXN],dep[MAXN],cur[MAXN];
void init()
{
    tol=0;
    cler(head,-1);
}
void addedge(int u,int v,int w,int rw=0)
{
    edge[tol].to=v,edge[tol].cap=w,edge[tol].flow=0,edge[tol].next=head[u];
    head[u]=toL++;
    edge[tol].to=u,edge[tol].cap=rw,edge[tol].next=head[v];
    head[v]=toL++;
}
int Q[MAXN];
void BFS(int star,int end)
{
    cler(dep,-1);
    cler(gap,0);
    gap[0]=-1;
    int front= 0,rear = 0;
    dep[end]=0;
    Q[rear++] = end;
    while(front!= rear)
    {
        int u=Q[front++];
        for(int i = head[u];i!=-1;i=edge[i].next)
        {
            int v=edge[i].to;
            if(dep[v]!= -1) continue;
            Q[rear++]= v;
            dep[v]=dep[u]+1;
            gap[dep[v]]++;
        }
    }
}
int S[MAXN];
int sap(int star,int end,int N)
{
    BFS(star,end);
    memcpy(cur,head,sizeof(head));
    int top=0,u=star,ans=0;
    while(dep[star]<N)
    {
        if(u==end)
        {
            int Min=INF;
            int inser;
            for(int i=0;i<top;i++)
                if(Min>edge[S[i]].cap-edge[S[i]].flow)
                {
                    Min=edge[S[i]].cap-edge[S[i]].flow;
                    inser=i;
                }
            for(int i=0;i<top;i++)
            {
                edge[S[i]].flow+=Min;
                edge[S[i]^1].flow-=Min;
            }
            ans+=Min;
            top=inser;
            u=edge[S[top]^1].to;
            continue;
        }
        bool flag = false;
        int v;
        for(int i=cur[u];i!=-1;i=edge[i].next)
        {
            v=edge[i].to;
            if(edge[i].cap-edge[i].flow&&dep[v]+1==dep[u])
            {
                flag = true;
                cur[u]=i;
                break;
            }
        }
        if(flag)
        {
            S[top++] = cur[u];
            u=v;
            continue;
        }
        int Min=N;
        for(int i= head[u];i!=-1;i=edge[i].next)
            if(edge[i].cap-edge[i].flow&&dep[edge[i].to]<Min)
            {
                Min=dep[edge[i].to];
                cur[u]=i;
            }
        gap[dep[u]]--;
        if(!gap[dep[u]]) return ans;
        dep[u]=Min+1;
        gap[dep[u]]++;
        if(u!=star) u=edge[S[--top]^1].to;
    }
    return ans;
}
int low[MAXN];
int u,v,c[MAXM],r[MAXM];
int main()
{
    #ifndef ONLINE_JUDGE
      freopen("in.txt",stdin);
    //freopen("out.txt",stdout);
    #endif
    int n,m;
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        cler(low,0);
        init();
        for(int i=0;i<m;i++)
        {
            scanf("%d%d%d%d",&u,&v,&c[i],&r[i]);
            addedge(u,r[i]-c[i]);
            low[v]+=c[i];
            low[u]-=c[i];
        }
        int star=0,end=n+1,sum=0;
        for(int i=1;i<=n;i++)
        {
            if(low[i]>0)
                addedge(star,i,low[i]),sum+=low[i];
            else
                addedge(i,end,-low[i]);
        }
       // cout<<sum<<" "<<sap(star,n+2)<<endl;
        if(sap(star,n+2)==sum)
        {
            puts("YES");
            for(int i=0;i<2*m;i+=2)
                printf("%d\n",edge[i].flow+c[i/2]);
        }
        else puts("NO");
    }
    return 0;
}