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MaximumBinaryTree.java
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MaximumBinaryTree.java
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package com.leetcode;
public class MaximumBinaryTree {
//https://leetcode.com/problems/maximum-binary-tree/
class Solution {
public TreeNode constructMaximumBinaryTree(int[] nums) {
int n = nums.length;
return constructTree(nums,0,n-1);
}
public TreeNode constructTree(int [] nums ,int left , int right){
int n = nums.length;
if(left < 0 || right >=n || left>right)
return null;
if(left == right) return new TreeNode(nums[left]);
int maxIndex = max(nums,left,right);
TreeNode node = new TreeNode(nums[maxIndex]);
node.left = constructTree(nums , left , maxIndex -1);
node.right = constructTree(nums , maxIndex +1 , right);
return node;
}
public int max(int[] nums , int left , int right){
int maxIndex = left;
for(int i = left ; i <= right ; i++){
if(nums[i] > nums[maxIndex]){
maxIndex = i;
}
}
return maxIndex;
}
}
//Definition for a binary tree node.
public class TreeNode {
int val;
TreeNode left;
TreeNode right;
TreeNode() {}
TreeNode(int val) { this.val = val; }
TreeNode(int val, TreeNode left, TreeNode right) {
this.val = val;
this.left = left;
this.right = right;
}
}
}