Easy
Given a 0-indexed m x n integer matrix matrix, create a new 0-indexed matrix called answer. Make answer equal to matrix, then replace each element with the value -1 with the maximum element in its respective column.
Return the matrix answer.
Example 1:

Input: matrix = [[1,2,-1],[4,-1,6],[7,8,9]]
Output: [[1,2,9],[4,8,6],[7,8,9]]
Explanation: The diagram above shows the elements that are changed (in blue).
Example 2:

Input: matrix = [[3,-1],[5,2]]
Output: [[3,2],[5,2]]
Explanation: The diagram above shows the elements that are changed (in blue).
Constraints:
m == matrix.lengthn == matrix[i].length2 <= m, n <= 50-1 <= matrix[i][j] <= 100class Solution {
fun modifiedMatrix(matrix: Array<IntArray>): Array<IntArray> {
for (i in matrix.indices) {
for (j in matrix[0].indices) {
if (matrix[i][j] == -1) {
var y = 0
for (ints in matrix) {
if (ints[j] > y) {
y = ints[j]
}
}
matrix[i][j] = y
}
}
}
return matrix
}
}