LeetCode/kt/minimum-operations-to-make-a-uni-value-grid.kt

class Solution {
    fun minOperations(
        grid: Array<IntArray>,
        x: Int,
    ): Int {
        if (grid.any { row -> row.any { it -> it % x != grid[0][0] % x } }) {
            // can't make them equal by a multiple of ‹x›
            return -1
        }

        val nums = grid.flatMap { it.asIterable() }.sorted()

        var ops = 0

        var (l, r) = 0 to nums.size - 1
        while (l < r) {
            when {
                l < nums.size - r - 1 -> {
                    ops += (l + 1) * (nums[l + 1] - nums[l]) / x
                    l++
                }
                else -> {
                    ops += (nums.size - r) * (nums[r] - nums[r - 1]) / x
                    r--
                }
            }
        }

        return ops
    }
}