一组数组，（中间允许出现重复的数字不按顺序的输入1-49，不超过100个元素），然后在这组数组中找相同的数字，输出他们重复的次数，如果是没有出现在数组（1-49这个范围）的就被忽略，就是不显示在输出内容里！
请各位帮帮忙，谢谢了。。。。。。

最简单的方式就是循环比较了，就是效率太低

双重循环。。。

#include <stdio.h>
int main (void)
{
    int i=0,j=0,n=0,a[100],x,b=0,max=1;
    int num[49],l=0,k=1;
    printf("Enter the balls that are drawn from the machine: \n");
    
    do
    {
        scanf("%d",&x);
        if (x>0&&x<49){
            a[i]=x;
            i++;
        }
    }while (i<100 && x>0 && x<49);
    
    printf("\n\nThe values from 1st ball to the 6th ball are: \n");

    for(j=0;j<6;j++)
        printf("%d ",a[j]);

    printf("\n\nThe 10th,20th and 30th balls: \n");
    printf("10th ball: %d\n20th ball: %d\n30th ball:%d\n",a[9],a[19],a[29]);


    for(j=0;j<i;j++){
        if (a[j] >40)
            b++;
    }
    
    printf("\nThe values are great than 40:%d\n",b);
    
    for(n=0;n<100;n++)
    {
        if(max<a[n])
            max=a[n];
        
    }
    printf("\nThe max vaule is : %d\n", max);


    for (l=0;l<100;l++)//频率
    num[a[l]-1]++;

    for(k=1;k<=49;k++)
        printf("ball %d was drawn %d times",k,num[k]);
    
        
        
        return 0;
}

可以帮我看下最后算频率那里哪里错了吗？？？？？
谢谢了

#include <stdio.h>
int main (void)
{
    int i=0,j=0,n=0,a[100],x,b=0,max=1;
    int num[49],l=0,k=1;
    printf("Enter the balls that are drawn from the machine: \n");
    
    do
    {
        scanf("%d",&x);
        if (x>0&&x<49){
            a[i]=x;
            i++;
        }
    }while (i<100 && x>0 && x<49);
    
    printf("\n\nThe values from 1st ball to the 6th ball are: \n");

    for(j=0;j<6;j++)
        printf("%d ",a[j]);

    printf("\n\nThe 10th,20th and 30th balls: \n");
    printf("10th ball: %d\n20th ball: %d\n30th ball:%d\n",a[9],a[19],a[29]);


    for(j=0;j<i;j++){
        if (a[j] >40)
            b++;
    }
    
    printf("\nThe values are great than 40:%d\n",b);
    
    for(n=0;n<100;n++)
    {
        if(max<a[n])
            max=a[n];
        
    }
    printf("\nThe max vaule is : %d\n", max);


    for (l=0;l<100;l++)//频率
    num[a[l]-1]++;

    for(k=1;k<=49;k++)
        printf("ball %d was drawn %d times",k,num[k]);
    
        
        
        return 0;
}

可以帮我看下哪里不对吗？？？谢谢了