Not the cleanest solution but so far this is the only solution I can think of for this easy LC problem.

class Solution {
fun isToeplitzMatrix(matrix: Array<IntArray>): Boolean {
var column = matrix.size - 1
var row = 0

while(column >= 0 && row < matrix[0].size){
var state = true
var num = -1
var x = row
var y = column
while(x < matrix[0].size && y < matrix.size){
val current = matrix[y++][x++]
if(num != -1) {
state = state and (num == current)
if(!state) return false
}
num = current
}

when {
column == 0 -> row++
else -> column--
}
}

return true
}
}

Runtime: 196 ms, faster than 60.00% of Kotlin online submissions for Toeplitz Matrix.
Memory Usage: 37.2 MB, less than 100.00% of Kotlin online submissions for Toeplitz Matrix.


This seems to be like a brute-force approach and I guess there’s another solution that can navigate through the diagonals in a more efficient way.