-
Notifications
You must be signed in to change notification settings - Fork 56
/
Solution.java
51 lines (46 loc) · 1.35 KB
/
Solution.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
package g0201_0300.s0222_count_complete_tree_nodes;
// #Easy #Depth_First_Search #Tree #Binary_Search #Binary_Tree #Binary_Search_II_Day_10
// #2022_07_04_Time_0_ms_(100.00%)_Space_50_MB_(37.43%)
import com_github_leetcode.TreeNode;
/*
* 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;
* }
* }
*/
public class Solution {
public int countNodes(TreeNode root) {
if (root == null) {
return 0;
}
int leftHeight = leftHeight(root);
int rightHeight = rightHeight(root);
// case 1: When Height(Left sub-tree) = Height(right sub-tree) 2^h - 1
if (leftHeight == rightHeight) {
return (1 << leftHeight) - 1;
} else {
return 1 + countNodes(root.left) + countNodes(root.right);
}
}
private int leftHeight(TreeNode root) {
if (root == null) {
return 0;
}
return 1 + leftHeight(root.left);
}
private int rightHeight(TreeNode root) {
if (root == null) {
return 0;
}
return 1 + rightHeight(root.right);
}
}