【bzoj3158】千钧一发 最小割

#include <cstdio>
#include <cstring>
#include <cmath>
#include <queue>
#define N 3000
#define M 3000000
#define inf 0x7fffffff
using namespace std;
queue<int> q;
int a[N] , v[N] , sa[N] , ta , sb[N] , tb , head[N] , to[M] , val[M] , next[M] , cnt = 1 , s , t , dis[N];
int gcd(int a , int b)
{
    return b ? gcd(b , a % b) : a;
}
bool judge(int x , int y)
{
    if(gcd(x , y) != 1) return 1;
    long long t = (long long)x * x + (long long)y * y;
    return (long long)sqrt(t) * (long long)sqrt(t) != t;
}
void add(int x , int y , int z)
{
    to[++cnt] = y , val[cnt] = z , next[cnt] = head[x] , head[x] = cnt;
    to[++cnt] = x , val[cnt] = 0 , next[cnt] = head[y] , head[y] = cnt;
}
bool bfs()
{
    int x , i;
    memset(dis,  0 , sizeof(dis));
    while(!q.empty()) q.pop();
    dis[s] = 1 , q.push(s);
    while(!q.empty())
    {
        x = q.front() , q.pop();
        for(i = head[x] ; i ; i = next[i])
        {
            if(val[i] && !dis[to[i]])
            {
                dis[to[i]] = dis[x] + 1;
                if(to[i] == t) return 1;
                q.push(to[i]);
            }
        }
    }
    return 0;
}
int dinic(int x , int low)
{
    if(x == t) return low;
    int temp = low , i , k;
    for(i = head[x] ; i ; i = next[i])
    {
        if(val[i] && dis[to[i]] == dis[x] + 1)
        {
            k = dinic(to[i] , min(temp , val[i]));
            if(!k) dis[to[i]] = 0;
            val[i] -= k , val[i ^ 1] += k;
            if(!(temp -= k)) break;
        }
    }
    return low - temp;
}
int main()
{
    int n , i , j , sum = 0;
    scanf("%d" , &n) , s = 0 , t = n + 1;
    for(i = 1 ; i <= n ; i ++ ) scanf("%d" , &a[i]);
    for(i = 1 ; i <= n ; i ++ )
    {
        scanf("%d" , &v[i]) , sum += v[i];
        if(a[i] % 2 == 1) sa[++ta] = i , add(s , i , v[i]);
        else sb[++tb] = i , add(i , t , v[i]);
    }
    for(i = 1 ; i <= ta ; i ++ )
        for(j = 1 ; j <= tb ; j ++ )
            if(!judge(a[sa[i]] , a[sb[j]]))
                add(sa[i] , sb[j] , inf);
    while(bfs()) sum -= dinic(s , inf);
    printf("%d" , sum);
    return 0;
}