这题不会做啊？求解答，求助

Question

Answer 1

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_ITEM_NUM 10000
#define MAX_VALUE 10000
#define MAX(a, b) ((a) > (b) ? (a) : (b))

int main(void)
{
    int item_num = 0;
    int count_each_num[MAX_VALUE] = {0};
    int index = 0;
    int value = 0;
    int max_value = 0;

    scanf("%d", &item_num);
    if(item_num < 1 || item_num > MAX_ITEM_NUM)
    {
        printf("please input number in 1 to %d !!!", MAX_ITEM_NUM);
        return -1;
    }

    //memset(count_each_num, 0, sizeof(count_each_num));
    for(index = 0; index < item_num; index++)
    {
        scanf("%d", &value);
        if(value >= MAX_VALUE)
        {
            printf("each number must less than %d !!!", MAX_VALUE);
            return -2;
        }
        max_value = MAX(value, max_value);
        count_each_num[value]++;
    }

    for(index = 0; index <= max_value; index++)
    {
        printf("%d:%d\n", index, count_each_num[index]);
    }

    return 0;
}