題目鏈接

遞歸 + 二叉樹

/*** 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) {return traversal(nums,0, nums.length - 1);}public TreeNode traversal(int[] nums,int left,int right){if(left > right){return null;}int maxIndex = left;for(int i = left + 1; i <= right; i++){if(nums[i] > nums[maxIndex]){maxIndex = i;}}TreeNode node = new TreeNode(nums[maxIndex]);node.left = traversal(nums,left,maxIndex - 1);node.right = traversal(nums,maxIndex + 1,right);return node;}
}