Hash入门

(HDOJ-1425 sort )

http://acm.hdu.edu.cn/showproblem.php?pid=1425

题目特点：
数据量大
数据在一定范围

#include<cstring>
#include<cstdio>
//using namespace std;
#define num 1000001
int Hash[num];

int main( )
{
    int n;
    int m;
    int mid = 500000;
    int max = -mid;
    int min = mid;
    int temp;
    while( scanf("%d %d",&n,&m) == 2 )
    {
        if( m > n )
            m = n;
        memset(Hash,0,sizeof(Hash));
        for( int i=0; i<n; i++ )
        {
            scanf("%d",&temp);
            if( temp > max )
                max = temp;
            if( temp < min )
                min = temp;
            ++Hash[temp+mid];
        }
        for( i=max+mid,min+=mid; i>=min&&m>0; i-- )
        {
            if( Hash[i] > 0 )
                if( --m )
                    printf("%d ",i-mid);
                else
                    printf("%d\n",i-mid);
        }
    }
    return 0;
}