Question Definition
You need to find the largest value in each row of a binary tree. Example:
Input:
1
/ \
3 2
/ \ \
5 3 9
Output: [1, 3, 9]
Java Solution
public List<Integer> largestValues(TreeNode root) {
List<Integer> result = new LinkedList<>();
if(root == null) return result;
Queue<TreeNode> queue = new LinkedList<>();
queue.offer(root);
while(!queue.isEmpty()){
int size = queue.size();
int max = Integer.MIN_VALUE;
for(int i = 0; i < size; i++){
TreeNode node = queue.poll();
max = Math.max(max, node.val);
if(node.left != null) queue.offer(node.left);
if(node.right != null) queue.offer(node.right);
}
result.add(max);
}
return result;
}
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