hdu 3189(网络流+二分枚举)

#include <stdio.h>
#include <algorithm>
#include <queue>
#include <string.h>
#include <math.h>
#include <iostream>
#include <math.h>
using namespace std;
const int N = 1100;
const int INF = 999999999;
struct Edge{
    int v,next;
    int w;
}edge[N*N];
struct Cow{
    int love[25];
}cow[N];
int head[N];
int level[N];
int graph[N][N],dis[N][N],cap[N];
int tot;
void init(){
    memset(head,-1,sizeof(head));
    tot=0;
}
void addEdge(int u,int v,int w,int &k){
    edge[k].v = v,edge[k].w=w,edge[k].next=head[u],head[u]=k++;
    edge[k].v = u,edge[k].w=0,edge[k].next=head[v],head[v]=k++;
}
int BFS(int src,int des){
    queue<int >q;
    memset(level,0,sizeof(level));
    level[src]=1;
    q.push(src);
    while(!q.empty()){
        int u = q.front();
        q.pop();
        if(u==des) return 1;
        for(int k = head[u];k!=-1;k=edge[k].next){
            int v = edge[k].v;
            int w = edge[k].w;
            if(level[v]==0&&w!=0){
                level[v]=level[u]+1;
                q.push(v);
            }
        }
    }
    return -1;
}
int dfs(int u,int des,int increaseRoad){
    if(u==des) return increaseRoad;
    int ret=0;
    for(int k=head[u];k!=-1;k=edge[k].next){
        int v = edge[k].v;
        int w = edge[k].w;
        if(level[v]==level[u]+1&&w!=0){
            int MIN = min(increaseRoad-ret,w);
            w = dfs(v,des,MIN);
            if(w>0){
            edge[k].w -=w;
            edge[k^1].w+=w;
            ret+=w;
            if(ret==increaseRoad) return ret;
            }else level[v] = -1;
        }
    }
    return ret;
}
int Dinic(int src,int des){
    int ans = 0;
    while(BFS(src,des)!=-1) ans+=dfs(src,des,INF);
    return ans;
}
int n,b,src,des;
int build(int t,int mid){
    init();
    for(int i=1;i<=b;i++){
        addEdge(src,i,cap[i],tot);
    }
    for(int i=1;i<=n;i++){
        addEdge(i+b,des,1,tot);
    }
    for(int i=t;i<=t+mid-1&&i<=b;i++){
        for(int j=1;j<=n;j++){
            addEdge(cow[j].love[i],j+b,1,tot);
        }
    }
    return Dinic(src,des);
}
int main(){
    scanf("%d%d",&n,&b);
    src = 0,des = n+b+1;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=b;j++){
            scanf("%d",&cow[i].love[j]);
        }
    }
    for(int i=1;i<=b;i++) scanf("%d",&cap[i]);
    int l =0,r = b;
    int ans = b;
    while(l<=r){
        int mid = (l+r)>>1;  ///差值
        bool flag = false;
        for(int i=1;i<=b;i++){ ///枚举最小值
            if(build(i,mid)==n) {
                flag = 1;
                break;
            }
        }
        if(flag) {
            ans = mid;
            r = mid-1;
        }else l = mid+1;
    }
    printf("%d\n",ans);
}