Given the root of a binary tree, return an array of the largest value in each row of the tree (0-indexed).
Example 1:
Input: root = [1,3,2,5,3,null,9] Output: [1,3,9]
Example 2:
Input: root = [1,2,3] Output: [1,3]
Constraints:
[0, 104].-231 <= Node.val <= 231 - 1/**
* 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 List<Integer> largestValues(TreeNode root) {
if (root == null)
return new ArrayList<>();
Queue<TreeNode> q = new LinkedList<>();
List<Integer> ans = new ArrayList<>();
q.offer(root);
while (!q.isEmpty()) {
int size = q.size(), maxm = Integer.MIN_VALUE;
for (int i = 0; i < size; i++) {
TreeNode node = q.poll();
maxm = Math.max(maxm, node.val);
if (node.left != null)
q.offer(node.left);
if (node.right != null)
q.offer(node.right);
}
ans.add(maxm);
}
return ans;
}
}/**
* 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 {
List<Integer> ans = new ArrayList<>();
public List<Integer> largestValues(TreeNode root) {
dfs(root, 0);
return ans;
}
private void dfs(TreeNode root, int depth){
if(root==null)
return;
if(depth==ans.size())
ans.add(root.val);
else ans.set(depth, Math.max(ans.get(depth), root.val));
dfs(root.left, depth+1);
dfs(root.right, depth+1);
}
}/**
* 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 {
List<Integer> ans = new ArrayList<>();
public List<Integer> largestValues(TreeNode root) {
dfs(root, 0);
return ans;
}
private void dfs(TreeNode root, int depth){
if(root==null)
return;
if(depth==ans.size())
ans.add(root.val);
else ans.set(depth, Math.max(ans.get(depth), root.val));
dfs(root.left, depth+1);
dfs(root.right, depth+1);
}
}