今日SGU 5.25

SGU 194

题意：无源汇有上下界的最大流

收获：https://wenku.baidu.com/view/0f3b691c59eef8c75fbfb35c.html

#include<bits/stdc++.h>
#define de(x) cout<<#x<<"="<<x<<endl;
#define dd(x) cout<<#x<<"="<<x<<" ";
#define rep(i,a,b) for(int i=a;i<(b);++i)
#define repd(i,a,b) for(int i=a;i>=(b);--i)
#define repp(i,a,b,t) for(int i=a;i<(b);i+=t)
#define ll long long
#define mt(a,b) memset(a,b,sizeof(a))
#define fi first
#define se second
#define inf 0x3f3f3f3f
#define INF 0x3f3f3f3f3f3f3f3f
#define pii pair<int,int>
#define pdd pair<double,double>
#define pdi pair<double,int>
#define mp(u,v) make_pair(u,v)
#define sz(a) (int)a.size()
#define ull unsigned long long
#define ll long long
#define pb push_back
#define PI acos(-1.0)
#define qc std::ios::sync_with_stdio(false)
#define db double
#define all(a) a.begin(),a.end()
const int mod = 1e9+7;
const int maxn = 2e2+5;
const double eps = 1e-6;
using namespace std;
bool eq(const db &a, const db &b) { return fabs(a - b) < eps; }
bool ls(const db &a, const db &b) { return a + eps < b; }
bool le(const db &a, const db &b) { return eq(a, b) || ls(a, b); }
ll gcd(ll a,ll b) { return a==0?b:gcd(b%a,a); };
ll lcm(ll a,ll b) { return a/gcd(a,b)*b; }
ll kpow(ll a,ll b) {ll res=1;a%=mod; if(b<0) return 1; for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll read(){
    ll x=0,f=1;char ch=getchar();
    while (ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
    while (ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
    return x*f;
}
int n,m,s,t,tot;
int b[maxn*maxn],c[maxn*maxn],in[maxn],out[maxn];
int pre[maxn],dis[maxn];
int q[maxn],l,r;
struct edge{
    int v,w,nt;
}e[maxn*maxn];
void init(){
    tot = 0;
    mt(pre,-1);mt(in,0);mt(out,0); 
}
void addedge(int u,int v,int w){
    e[tot].v=v;e[tot].w=w;e[tot].nt=pre[u];
    pre[u]=tot++;
    e[tot].v=u;e[tot].w=0;e[tot].nt=pre[v];
    pre[v]=tot++;
}
bool bfs(){
    mt(dis,-1);
    dis[s]=0;
    l = r = 0;
    q[r++] = s;
    while(l<r){
        int u=q[l++];
        for(int i=pre[u];~i;i=e[i].nt){
            int v=e[i].v,w=e[i].w;
            if(dis[v]==-1&&w>0){
                dis[v]=dis[u]+1;
                q[r++] = v;
            }
        }
    }
    return dis[t]!=-1;
}
int dfs(int u,int cp){
    if(u==t||!cp) return cp;
    int tmp=cp;
    for(int i=pre[u];~i;i=e[i].nt){
        int v=e[i].v,w=e[i].w;
        if(dis[v]==dis[u]+1&&w>0){
            int tt=dfs(v,min(tmp,w));
            e[i].w-=tt;
            e[i^1].w+=tt;
            tmp-=tt;
            if(tmp<=0) return cp;
        }
    }
    dis[u]=inf;
    return cp-tmp;
}
int dinic(){
    int ret = 0;
    while(bfs()) ret+=dfs(s,inf);
    return ret;
}
int main(){
    int u,v;
    init();
    scanf("%d%d",&n,&m);
    rep(i,0,m) scanf("%d%d%d%d",&u,&v,&b[i],&c[i]),addedge(u,v,c[i]-b[i]),in[v] += b[i],out[u] += b[i];
    s = 0;t = n + 1;
    int ans = 0;
    rep(i,1,n+1) if(out[i] - in[i] > 0) addedge(i,t,out[i] - in[i]),ans += out[i] - in[i];
    else addedge(s,i,in[i] - out[i]);
    if(ans!=dinic())  return puts("NO"),0;
    puts("YES");
    rep(i,0,m) printf("%d\n",b[i] + e[i << 1 | 1].w);
    return 0;
}