最小堆

如下：

heapify每次把当前分支的最小的放在top

然后遍历每个“小树”，即可。。

#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
const int maxn = 100005;
#define LEFT( x ) ((x<<1)+1)
#define RIGHT( x ) ((x+1)<<1)
#define PARENT( x ) ((x-1)/2)//((x+1)>>1-1)
int a[ maxn ];
void heapify( int pos,int n ){
    int pos_l,pos_r,tmp;
    pos_l = LEFT( pos );
    pos_r = RIGHT( pos );
    tmp = pos;
    if( pos_l<=n&&a[ pos_l ]<a[ pos ] ){
        tmp = pos_l;
    }
    if( pos_r<=n&&a[ pos_r ]<a[ tmp ] ){
        tmp = pos_r;
    }//GET THE MIN
    if( tmp!=pos ){
        swap( a[ tmp ],a[ pos ] );
        heapify( tmp,n );
    }
    return ;
}

int build_the_min_top( int n ){
    for( int i=(int)PARENT( n );i>=0;i-- ){
        heapify( i,n );
    }
    return a[ 0 ];//return the min
}

int main(){
    int ca;
    scanf("%d",&ca);
    for( int t=0;t<ca;t++ ){
        int num;
        scanf("%d",&num);
        printf("case #%d:\n",t);
        int n = 0;
        while( num-- ){
            char s[5];
            scanf("%s",s);
            if( s[0]=='B' ){
                int tmp;
                scanf("%d",&tmp);
                a[ n++ ] = tmp;
            }
            else {
                printf("%d\n",build_the_min_top( n-1 ) );
                swap( a[ 0 ],a[ n-1 ] );
                n--;//remove the min to the tail
            }
        }
    }
    return 0;
}