LeetCode 1742. Maximum Number of Balls in a Box

You are working in a ball factory where you have n balls numbered from lowLimit up to highLimit inclusive (i.e., n == highLimit – lowLimit + 1), and an infinite number of boxes numbered from 1 to infinity.

Your job at this factory is to put each ball in the box with a number equal to the sum of digits of the ball’s number. For example, the ball number 321 will be put in the box number 3 + 2 + 1 = 6 and the ball number 10 will be put in the box number 1 + 0 = 1.

Given two integers lowLimit and highLimit, return the number of balls in the box with the most balls.

Example 1:

Input: lowLimit = 1, highLimit = 10
Output: 2
Explanation:
Box Number: 1 2 3 4 5 6 7 8 9 10 11 …
Ball Count: 2 1 1 1 1 1 1 1 1 0 0 …
Box 1 has the most number of balls with 2 balls.
Example 2:

Input: lowLimit = 5, highLimit = 15
Output: 2
Explanation:
Box Number: 1 2 3 4 5 6 7 8 9 10 11 …
Ball Count: 1 1 1 1 2 2 1 1 1 0 0 …
Boxes 5 and 6 have the most number of balls with 2 balls in each.
Example 3:

Input: lowLimit = 19, highLimit = 28
Output: 2
Explanation:
Box Number: 1 2 3 4 5 6 7 8 9 10 11 12 …
Ball Count: 0 1 1 1 1 1 1 1 1 2 0 0 …
Box 10 has the most number of balls with 2 balls.

Constraints:

1 <= lowLimit <= highLimit <= 105

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/**
 * @param {number} lowLimit
 * @param {number} highLimit
 * @return {number}
 */

const getSum = (val) => {
    let sum = 0;
    while(val>0){
        let mod = val % 10;
        sum += mod;
        val = (val - mod) / 10;
    }
    return sum;
}
var countBalls = function(lowLimit, highLimit) {
    let box = {}
    for(let i=lowLimit;i<=highLimit;++i){
        let n = getSum(i);
        box[n] = (box[n] || 0) + 1;
    }
    let max = 0;
    for(let k in box){
        if(box[k]>max){
            max = box[k];
        }
    }
    return max
};


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