【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].flow=0,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", "r", stdin);    //freopen("out.txt", "w", 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,v,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,end,n+2)<<endl;        if(sap(star,end,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;}