Package g1901_2000.s1901_find_a_peak_element_ii

Class Solution

  • public class Solution
extends Object
    1901 - Find a Peak Element II.

    Medium

    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 [i,j].

    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.

    Example 1:

    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.

    Example 2:

    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.

    Constraints:

    • m == mat.length
    • n == mat[i].length
    • 1 <= m, n <= 500
    • 1 <= mat[i][j] <= 105
    • No two adjacent cells are equal.

    • Constructor Detail

      • Solution

        public Solution()

    • Method Detail

      • findPeakGrid

        public int[] findPeakGrid​(int[][] mat)