題目描述：

https://leetcode-cn.com/problems/maximum-number-of-balls-in-a-box/

Java程式碼：

class Solution {
    public int countBalls(int l, int h) {
        int[] cnt=new int[46];
        for(int i=l;i<=h;i++){
            int num=i,bitSum=0;
            while(num!=0){
                bitSum+=num%10;
                num=num/10;
            }
            cnt[bitSum]++;
        }
        int ans=0;
        for(int e:cnt)if(ans<e)ans=e;
        return ans;
    }
}

Java程式碼二：

class Solution {
    public int countBalls(int l, int h) {
        int[] cnt=new int[46],cache=new int[h+1];
        for(int i=1;i<=h;i++)cache[i]=cache[i/10]+i%10;
        for(int i=l;i<=h;i++)cnt[cache[i]]++;
        int ans=0;
        for(int e:cnt)if(ans<e)ans=e;
        return ans;
    }
}

Java程式碼三：

class Solution {
    public int getBitSum(int n){
        int bitSum=0;
        while(n!=0){
            bitSum+=n%10;
            n/=10;
        }
        return bitSum;
    }
    public int countBalls(int l, int h) {
        int[] cnt=new int[46];
        int ans=0,bitSum=getBitSum(l);
        for(int i=l;i<=h;i++){
            if(i%10==0)bitSum=getBitSum(i);
            cnt[bitSum++]++;
        }
        for(int e:cnt)if(ans<e)ans=e;
        return ans;
    }
}

class Solution {
    public int getBitSum(int n){
        int bitSum=0;
        while(n!=0){
            bitSum+=n%10;
            n/=10;
        }
        return bitSum;
    }
    public int countBalls(int l, int h) {
        int[] cnt=new int[46];
        int ans=0,bitSum=getBitSum(l);
        for(int i=l;i<=h;i++){
            if(i%10==0){
                int num=i/10;
                bitSum=0;
                while(num!=0){
                    bitSum+=num%10;
                    num/=10;
                }
            }
            cnt[bitSum++]++;
        }
        for(int e:cnt)if(ans<e)ans=e;
        return ans;
    }
}