tens-digit-sorting.md

Tens Digit Sorting

Problem Description

Given an array A of N integers. Sort the array in increasing order of the value at the tens place digit of every number.

• If a number has no tens digit, we can assume value to be 0.
• If 2 numbers have same tens digit, in that case number with max value will come first
• Solution should be based on comparator.

Problem Constraints

1 <= N <= 105
1 <= A[i] <= 109

Input Format

First argument A is an array of integers.

Output Format

Return the array after sorting

Example Input

Input 1:
A = [15, 11, 7, 19]

Input 2:
A = [2, 24, 22, 19]

Example Output

Output 1:
[7, 19, 15, 11]

Output 2:
[2, 19, 24, 22]

Example Explanation

Explanation 1:
The sorted order is [7, 19, 15, 11]. The tens digit of 7 is 0, and that of 19, 15 and 11 is 1.

Explanation 2:
The sorted order is [2, 19, 24, 22]. The tens digit of 2 is 0, that of 19 is 1 and that of 22 and 24 is 2.

Output

function sortByTensDigit(A) {
    // Function to extract tens digit
    function getTensDigit(num) {
        return Math.floor((num % 100) / 10);
    }

    // Custom comparator
    A.sort((a, b) => {
        let tensA = getTensDigit(a);
        let tensB = getTensDigit(b);
        
        if (tensA !== tensB) {
            return tensA - tensB;
        } else {
            return b - a;
        }
    });

    return A;
}

// Example usage
console.log(sortByTensDigit([15, 11, 7, 19])); // Output: [7, 19, 15, 11]
console.log(sortByTensDigit([2, 24, 22, 19])); // Output: [2, 19, 24, 22]