2661. First Completely Painted Row or Column

You are given a 0-indexed integer array arr, and an m x n integer matrix mat. arr and mat both contain all the integers in the range [1, m * n]. Go through each index i in arr starting from index 0 and paint the cell in mat containing the integer arr[i]. Return the smallest index i at which either a row or a column will be completely painted in mat. Example 1: Input: arr = [1,3,4,2], mat = [