hdu 3335 最大独立集

有整除关系就建边，然后求最大独立集。

AC代码：

#include <iostream>
#include <cstring>
#include <cstdio>
using namespace std;

const int N = 1001;
const int M = 1000000;
bool visit[N];
__int64 a[N];
int head[N];
int mark[N];
int n, e;

struct Edge
{
    int v, next;
} edge[M];

void addEdge( int u, int v )
{
    edge[e].v = v;
    edge[e].next = head[u];
    head[u] = e++;
}

int dfs( int u )
{
    for ( int i = head[u]; i != -1; i = edge[i].next )
    {
        int v = edge[i].v;
        if ( !visit[v] )
        {
            visit[v] = true;
            if ( mark[v] == -1 || dfs( mark[v] ) )
            {
                mark[v] = u;
                return 1;
            }
        }
    }
    return 0;
}

int hunagry()
{
    memset( mark, -1, sizeof(mark) );
    int res = 0;
    for ( int i = 1; i <= n; i++ )
    {
        memset( visit, 0, sizeof(visit) );
        res += dfs(i);
    }
    return res;
}

int main()
{
    int t;
    scanf("%d", &t);
    while ( t-- )
    {
        e = 0;
        memset( head, -1, sizeof(head) );
        scanf("%d", &n);
        for ( int i = 1; i <= n; i++ )
        {
            scanf("%I64d", a + i);
            for ( int j = i - 1; j > 0; j-- )
            {
                if ( a[i] % a[j] == 0 || a[j] % a[i] == 0 )
                {
                    addEdge( j, i );
                }
            }
        }
        int ans = n - hunagry();
        printf("%d\n", ans);
    }
    return 0;
}