c语言队列问题

#include <stdio.h>

int main( void )
{
    // 队列
    unsigned queue[100000];
    size_t queue_begin = 0;
    size_t queue_end = 0;
    // [0,1000]中每个数字的数量
    unsigned count[1001] = { 0 };
    // 有多少种不同的数字
    unsigned variety = 0;

    unsigned n;
    scanf( "%u", &n );
    while( n-- )
    {
        unsigned action;
        scanf( "%u", &action );
        switch( action )
        {
        case 1:
            printf( "%u\n", variety );
            break;
        case 2:
            {
            unsigned push;
            scanf( "%u", &push );
            queue[queue_end++] = push;
            if( count[push] == 0 )
                ++variety;
            ++count[push];
            }
            break;
        case 3:
            {
            unsigned pop = queue[queue_begin++];
            --count[pop];
            if( count[pop] == 0 )
                --variety;
            }
            break;
        }
    }
}