/
Solution.java
executable file
·58 lines (48 loc) · 1.35 KB
/
Solution.java
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/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public TreeNode sortedArrayToBST(int[] num) {
if (num == null || num.length == 0)
return null;
return helper(num, 0, num.length - 1);
}
private TreeNode helper(int[] num, int l, int r) {
if (l > r)
return null;
int m = (l + r) / 2;
TreeNode root = new TreeNode(num[m]);
root.left = helper(num, l, m - 1);
root.right = helper(num, m + 1, r);
return root;
}
}
/**
* Definition for binary tree
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Solution {
//TreeNode
public TreeNode sortedArrayToBST(int[] num) {
if(num.length == 0)
return null;
if(num.length == 1)
return new TreeNode(num[0]);
int mid = num.length / 2;
TreeNode root = new TreeNode(num[mid]);
root.left = sortedArrayToBST(Arrays.copyOfRange(num, 0, mid));
root.right = sortedArrayToBST(Arrays.copyOfRange(num, mid + 1, num.length));
return root;
}
}