654. Maximum Binary Tree

/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
public TreeNode constructMaximumBinaryTree(int[] nums) {
return getMaximumNodeHelper(nums,0,nums.length - 1, new TreeNode(0));
}
public static TreeNode getMaximumNodeHelper(int[] nums, int start, int end, TreeNode n){
if(start == end && start end) return null;
int maxValue = Integer.MIN_VALUE;
int maxIndex = 0;
for (int i = start; i maxValue){
maxValue = nums[i];
maxIndex = i;
}
}
n.val = maxValue;
///
int maxValueRight = Integer.MIN_VALUE;
int maxIndexRight = maxIndex+1;
for (int i = maxIndex+1; i maxValueRight){
maxValueRight = nums[i];
maxIndexRight = i;
}
}
n.right = getMaximumNodeHelper(nums,maxIndex+1,end,new TreeNode(maxValueRight));
////
int maxValueLeft = Integer.MIN_VALUE;
int maxIndexLeft = maxIndex+1;
for (int i = start; i maxValueLeft){
maxValueLeft = nums[i];
maxIndexLeft = i;
}
}
n.left = getMaximumNodeHelper(nums,start,maxIndex-1,new TreeNode(maxValueLeft));
return n;
}
}

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