177题 Convert Sorted Array to Binary Search Tree With Minimal Height.

最小高度二叉搜索树构造

最新推荐文章于 2025-12-13 12:19:21 发布

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该博客讨论如何从有序数组构建最小高度的二叉搜索树。解决方案通过递归地将数组分成左右子数组来实现，每次选择中间元素作为根节点，确保平衡。

Convert Sorted Array to Binary Search Tree With Minimal Height.

Description
Given a sorted (increasing order) array, Convert it to a binary search tree with minimal height.

/**
 * Definition of TreeNode:
 * public class TreeNode {
 *     public int val;
 *     public TreeNode left, right;
 *     public TreeNode(int val) {
 *         this.val = val;
 *         this.left = this.right = null;
 *     }
 * }
 */


public class Solution {
    /*
     * @param A: an integer array
     * @return: A tree node
     */
    public TreeNode sortedArrayToBST(int[] A) {
        // write your code here
        if(A == null){
            return null; 
        }
        int n = A.length - 1 ;
        return toBST(A, 0 , n) ;
        
    }
    public TreeNode toBST(int[] A , int L , int R){
        if(L > R){
          return null ;
        }
        int mid = (L + R) >>>1 ;
        TreeNode left = toBST(A, L , mid-1);
        TreeNode curt = new TreeNode(A[mid]);
        curt.left = left ;
        TreeNode right = toBST(A, mid+1 , R);
        curt.right = right ;
        return curt ;
    }
}