A peak element in a 2D grid is an element that is strictly greater than all of its adjacent neighbors to the left, right, top, and bottom.
Given a 0-indexed
m x n matrix
mat where no two adjacent cells are equal, find any peak element
mat[i][j] and return the length 2 array
You may assume that the entire matrix is surrounded by an outer perimeter with the value
-1 in each cell.
You must write an algorithm that runs in
O(m log(n)) or
O(n log(m)) time.
Input: mat = [[1,4],[3,2]] Output: [0,1] Explanation: Both 3 and 4 are peak elements so [1,0] and [0,1] are both acceptable answers.
Input: mat = [[10,20,15],[21,30,14],[7,16,32]] Output: [1,1] Explanation: Both 30 and 32 are peak elements so [1,1] and [2,2] are both acceptable answers.
m == mat.length
n == mat[i].length
1 <= m, n <= 500
1 <= mat[i][j] <= 105