板子题
给你一张二分图，一边n个点，另一边m个点，k条边，问你能不能通过删边，使得所有点的度数都在[L,R]
#include<bits/stdc++.h>
#define FIN freopen("input.txt","r",stdin)
#define ll long long
#define mod 1000000007
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
#define inf 0x3f3f3f3f
#define INF 0x3f3f3f3f3f3f3f3f
const int maxn = 100005;
using namespace std;
int cnt,s,t,n,m,k;
int head[maxn],Next[maxn*20],to[maxn*20];
int flow[maxn*20],dep[maxn],cur[maxn],mp[405][405];
int dir[8][2]={1,2,1,-2,-1,2,-1,-2,-2,-1,-2,1,2,1,2,-1};
inline void add(int u,int v,int w){
Next[cnt]=head[u];
head[u]=cnt;
to[cnt]=v;
flow[cnt++]=w;
Next[cnt]=head[v];
head[v]=cnt;
to[cnt]=u;
flow[cnt++]=0;
}
int dfs(int u,int cost){
if(u==t) return cost;
for(int &i=cur[u];i!=-1;i=Next[i]){
if(dep[to[i]]==dep[u]+1&&flow[i]>0){
int dis=dfs(to[i],min(flow[i],cost));
if(dis>0){
flow[i]-=dis;
flow[i^1]+=dis;
return dis;
}
}
}
return 0;
}
int bfs(){
queue<int> q;
q.push(s);
memset(dep,0,sizeof(dep));
dep[s]=1;
while(!q.empty()){
int u=q.front();
q.pop();
for(int i=head[u];i!=-1;i=Next[i]){
if(flow[i]>0&&dep[to[i]]==0){
dep[to[i]]=dep[u]+1;
q.push(to[i]);
}
}
}
if(dep[t]>0) return 1;
return 0;
}
int dicnic(){
int ans=0;
while(bfs()){
int cost;
for(int i=0;i<=t+2;i++){
cur[i]=head[i];
}
while(cost=dfs(s,inf))
ans+=cost;
}
return ans;
}
int p[200005];
void init(){
memset(head,-1,sizeof(head));
memset(p,0,sizeof(p));
cnt=0;
}
int main(){
int cas=0;
while(~scanf("%d %d %d",&n,&m,&k)){
init();
int l,r;
int ss=0; //源点
int tt=n+m+1;//汇点
s=n+m+2;//超级源点
t=n+m+3;//超级汇点
int sum=0;
scanf("%d %d",&l,&r);
for(int i=1;i<=k;i++){
int u,v;
scanf("%d %d",&u,&v);
add(u,v+n,1);
}
for(int i=1;i<=n;i++){
add(ss,i,r-l);
p[i]+=l;
}
for(int i=1;i<=m;i++){
add(i+n,tt,r-l);
p[i+n]-=l;
}
for(int i=1;i<=n+m;i++){
if(p[i]<0) add(i,t,-p[i]);
else add(s,i,p[i]),sum+=p[i];
// printf("%d ---> %d\n", i,p[i]);
}
add(tt,ss,inf);
printf("Case %d: ",++cas);
if(sum==dicnic())
puts("Yes");
else puts("No");
}
}