LeetCode in Kotlin

3546. Equal Sum Grid Partition I

Medium

You are given an m x n matrix grid of positive integers. Your task is to determine if it is possible to make either one horizontal or one vertical cut on the grid such that:

• Each of the two resulting sections formed by the cut is non-empty.
• The sum of the elements in both sections is equal.

Return true if such a partition exists; otherwise return false.

Example 1:

Input: grid = [[1,4],[2,3]]

Output: true

Explanation:

A horizontal cut between row 0 and row 1 results in two non-empty sections, each with a sum of 5. Thus, the answer is true.

Example 2:

Input: grid = [[1,3],[2,4]]

Output: false

Explanation:

No horizontal or vertical cut results in two non-empty sections with equal sums. Thus, the answer is false.

Constraints:

• 1 <= m == grid.length <= 105
• 1 <= n == grid[i].length <= 105
• 2 <= m * n <= 105
• 1 <= grid[i][j] <= 105

Solution

class Solution {
    fun canPartitionGrid(grid: Array<IntArray>): Boolean {
        val n = grid.size
        val m = grid[0].size
        var totalRowSum = 0L
        val prefixRowWise = LongArray(n)
        val prefixColWise = LongArray(m)
        for (i in 0..<n) {
            for (j in 0..<m) {
                val v = grid[i][j]
                prefixRowWise[i] += v.toLong()
                prefixColWise[j] += v.toLong()
            }
        }
        for (r in prefixRowWise) {
            totalRowSum += r
        }
        val totalColSum: Long = totalRowSum
        var currentRowUpperSum = 0L
        for (i in 0..<n - 1) {
            currentRowUpperSum += prefixRowWise[i]
            val lowerSegmentSum = totalRowSum - currentRowUpperSum
            if (currentRowUpperSum == lowerSegmentSum) {
                return true
            }
        }
        var currentColLeftSum = 0L
        for (j in 0..<m - 1) {
            currentColLeftSum += prefixColWise[j]
            val rightSegmentSum = totalColSum - currentColLeftSum
            if (currentColLeftSum == rightSegmentSum) {
                return true
            }
        }
        return false
    }
}

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