bzoj3275 Number（最大点权独立集）

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>
#include <cmath>
using namespace std;
#define ll long long
#define inf 0x3f3f3f3f
#define N 3010
inline int read(){
int 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,col
,h
,num=1,T=3001,lev
,ans=0,tot=0,cur
,a
;
struct edge{
int to,next,val;
}data[5000000];
inline void add(int x,int y,int val){
data[++num].to=y;data[num].next=h[x];h[x]=num;data[num].val=val;
data[++num].to=x;data[num].next=h[y];h[y]=num;data[num].val=0;
}
inline bool bfs(){
queue<int>q;memset(lev,0,sizeof(lev));
lev[0]=1;q.push(0);
while(!q.empty()){
int x=q.front();q.pop();
for(int i=h[x];i;i=data[i].next){
int y=data[i].to;if(lev[y]||!data[i].val) continue;
lev[y]=lev[x]+1;if(y==T) return 1;q.push(y);
}
}return 0;
}
inline int dinic(int x,int low){
if(x==T) return low;int tmp=low;
for(int &i=cur[x];i;i=data[i].next){
int y=data[i].to;if(lev[y]!=lev[x]+1||!data[i].val) continue;
int res=dinic(y,min(data[i].val,tmp));
if(!res) lev[y]=0;else tmp-=res,data[i].val-=res,data[i^1].val+=res;
if(!tmp) return low;
}return low-tmp;
}
inline int gcd(int x,int y){return y==0?x:gcd(y,x%y);}
inline bool issqr(int x){int tmp=sqrt(x);return tmp*tmp==x;}
int main(){
//  freopen("a.in","r",stdin);
n=read();for(int i=1;i<=n;++i) a[i]=read(),tot+=a[i];
for(int i=1;i<=n;++i){
if(a[i]&1) add(0,i,a[i]);
else{add(i,T,a[i]);continue;}
for(int j=1;j<=n;++j){
if(i==j||gcd(a[i],a[j])!=1) continue;
if(!issqr(a[i]*a[i]+a[j]*a[j])) continue;
add(i,j,inf);
}
}while(bfs()){memcpy(cur,h,sizeof(cur));ans+=dinic(0,inf);}
printf("%d\n",tot-ans);
return 0;
}