LeetCode in Kotlin

3265. Count Almost Equal Pairs I

Medium

You are given an array nums consisting of positive integers.

We call two integers x and y in this problem almost equal if both integers can become equal after performing the following operation at most once:

• Choose either x or y and swap any two digits within the chosen number.

Return the number of indices i and j in nums where i < j such that nums[i] and nums[j] are almost equal.

Note that it is allowed for an integer to have leading zeros after performing an operation.

Example 1:

Input: nums = [3,12,30,17,21]

Output: 2

Explanation:

The almost equal pairs of elements are:

• 3 and 30. By swapping 3 and 0 in 30, you get 3.
• 12 and 21. By swapping 1 and 2 in 12, you get 21.

Example 2:

Input: nums = [1,1,1,1,1]

Output: 10

Explanation:

Every two elements in the array are almost equal.

Example 3:

Input: nums = [123,231]

Output: 0

Explanation:

We cannot swap any two digits of 123 or 231 to reach the other.

Constraints:

• 2 <= nums.length <= 100
• 1 <= nums[i] <= 106

Solution

@Suppress("NAME_SHADOWING")
class Solution {
    fun countPairs(nums: IntArray): Int {
        var ans = 0
        for (i in 0 until nums.size - 1) {
            for (j in i + 1 until nums.size) {
                if (nums[i] == nums[j] ||
                    ((nums[j] - nums[i]) % 9 == 0 && check(nums[i], nums[j]))
                ) {
                    ans++
                }
            }
        }
        return ans
    }

    private fun check(a: Int, b: Int): Boolean {
        var a = a
        var b = b
        val ca = IntArray(10)
        val cb = IntArray(10)
        var d = 0
        while (a > 0 || b > 0) {
            if (a % 10 != b % 10) {
                d++
                if (d > 2) {
                    return false
                }
            }
            ca[a % 10]++
            cb[b % 10]++
            a /= 10
            b /= 10
        }
        return d == 2 && areEqual(ca, cb)
    }

    private fun areEqual(a: IntArray, b: IntArray): Boolean {
        for (i in 0..9) {
            if (a[i] != b[i]) {
                return false
            }
        }
        return true
    }
}

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