LeetCode 2445: Number of Nodes With Value One Solution
Master LeetCode problem 2445 (Number of Nodes With Value One), a medium challenge, with our optimized solutions in Java, C++, and Python. Explore detailed explanations, test your code in our interactive editor, and prepare for coding interviews.
2445. Number of Nodes With Value One
Problem Explanation
Explanation
To solve this problem, we will traverse the given binary tree in a post-order manner. At each node, we will calculate the number of nodes with value 1 in the left and right subtrees. Then, we will update the count of nodes with value 1 in the current subtree and return this count to the parent node.
We will define a recursive function that takes a node as input and returns the count of nodes with value 1 in the subtree rooted at that node.
Solution Code
class TreeNode {
int val;
TreeNode left;
TreeNode right;
TreeNode(int x) {
val = x;
}
}
class Solution {
public int countNodesWithOne(TreeNode root) {
if (root == null) {
return 0;
}
int[] count = new int[1];
countNodes(root, count);
return count[0];
}
private int countNodes(TreeNode node, int[] count) {
if (node == null) {
return 0;
}
int leftCount = countNodes(node.left, count);
int rightCount = countNodes(node.right, count);
if (node.val == 1) {
count[0]++;
}
return leftCount + rightCount + (node.val == 1 ? 1 : 0);
}
}Try It Yourself
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