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Valid Mountain Array

Given an array of integers  arr , return   true  if and only if it is a valid mountain array . Recall that arr is a mountain array if and only if: arr.length >= 3 There exists some  i  with  0 < i < arr.length - 1  such that: arr[0] < arr[1] < ... < arr[i - 1] < A[i] arr[i] > arr[i + 1] > ... > arr[arr.length - 1]   Example 1: Input: arr = [2,1] Output: false Example 2: Input: arr = [3,5,5] Output: false Example 3: Input: arr = [0,3,2,1] Output: true   Constraints: 1 <= arr.length <= 10 4 0 <= arr[i] <= 10 4 Solution: class Solution {     public boolean validMountainArray(int[] arr) {         int n = arr.length, i = 0, j = n - 1;         while (i+1  < n &...