Maximum Binary Tree LeetCode solution in Java

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class Solution {
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  public TreeNode constructMaximumBinaryTree(int[] nums) {
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    TreeNode root = construct(nums, 0, nums.length - 1);
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    return root;
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  }
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  private TreeNode construct(int[] nums, int start, int end) {
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    if (start > end) return null;
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    if (start == end) return new TreeNode(nums[start]);
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    int maxIdx = findMax(nums, start, end);
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    TreeNode root = new TreeNode(nums[maxIdx]);
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    root.left = construct(nums, start, maxIdx - 1);
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    root.right = construct(nums, maxIdx + 1, end);
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    return root;
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  }
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  private int findMax(int[] arr, int low, int high) {
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    int idx = -1, max = Integer.MIN_VALUE;
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    for (int i = low; i <= high; ++i)
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      if (arr[i] > max) {
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        max = arr[i];
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        idx = i;
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      }
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    return idx;
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  }
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}