【bzoj 1458】士兵占领

解题思路

#include<algorithm>
#include<iostream>
#include<cmath>
#include<cstring>
#include<string>
#include<cstdio>
#include<cstdlib>
#include<queue>
using namespace std;
int hed[205],nex[40005],lb[40005],cap[40005];
int L[105],C[105],suml[105],sumc[105];
int dep[205],pa[105][105];
int n,m,pk,s=201,t=202,lo=-1,mx=2147483640;
int dfs(int x,int num){
if(num==0 || x==t) return num;
int c=0;
for(int i=hed[x];i!=-1;i=nex[i])
if(cap[i] && dep[lb[i]]==dep[x]+1){
int f=dfs(lb[i],min(num,cap[i]));
c+=f;
num-=f;
cap[i]-=f;
cap[i^1]+=f;
if(num==0) break;
}
return c;
}
bool bfs(){
memset(dep,0,sizeof(dep));
queue<int>q;
q.push(s);
dep[s]=1;
while(!q.empty()){
int x=q.front();q.pop();
for(int i=hed[x];i!=-1;i=nex[i])
if(cap[i] && !dep[lb[i]]){
dep[lb[i]]=dep[x]+1;
q.push(lb[i]);
}
}
return dep[t];
}
int dinic_(){
int c=0;
while(bfs()) c+=dfs(s,mx);
return c;
}
void add(int x,int y,int num){
lo++;
nex[lo]=hed[x];
hed[x]=lo;
lb[lo]=y;
cap[lo]=num;
}
int main(){
int xx,yy;
memset(hed,-1,sizeof(hed));
scanf("%d%d%d",&n,&m,&pk);
for(int i=1;i<=n;i++) {scanf("%d",&L[i]);suml[i]=m;}
for(int i=1;i<=m;i++) {scanf("%d",&C[i]);sumc[i]=n;}
for(int i=1;i<=pk;i++){
scanf("%d%d",&xx,&yy);
pa[xx][yy]=1;
suml[xx]--;
sumc[yy]--;
}
for(int i=1;i<=n;i++)
for(int j=1;j<=m;j++)
if(!pa[i][j]){
add(i,n+j,1);
add(n+j,i,0);
}
for(int i=1;i<=n;i++) {add(s,i,suml[i]-L[i]);add(i,s,0);}
for(int i=1;i<=m;i++) {add(i+n,t,sumc[i]-C[i]);add(t,i+n,0);}
printf("%d",n*m-pk-dinic_());
return 0;
}