/**
* 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;
* }
* }
*/
class Solution {
public TreeNode constructMaximumBinaryTree(int[] nums) {
if(nums == null || nums.length == 0) {
return null;
}
return help(nums, 0, nums.length - 1);
}
public TreeNode help(int[] nums, int start, int end) {
if(start > end) {
return null;
}
int maxIndex = start;//此处必须取 start和end之间的一个值
for(int i = start; i <= end; i++) {
if(nums[i] > nums[maxIndex]) {
maxIndex = i;
}
}
TreeNode root = new TreeNode(nums[maxIndex]);
root.left = help(nums, start, maxIndex - 1);
root.right = help(nums, maxIndex + 1, end);
return root;
}
}