LeetCode Solutions
515. Find Largest Value in Each Tree Row
Time: $O(n)$ Space: $O(n)$
class Solution {
public:
vector<int> largestValues(TreeNode* root) {
if (root == nullptr)
return {};
vector<int> ans;
queue<TreeNode*> q{{root}};
while (!q.empty()) {
int maxi = INT_MIN;
for (int sz = q.size(); sz > 0; --sz) {
TreeNode* node = q.front();
q.pop();
maxi = max(maxi, node->val);
if (node->left)
q.push(node->left);
if (node->right)
q.push(node->right);
}
ans.push_back(maxi);
}
return ans;
}
};
class Solution {
public List<Integer> largestValues(TreeNode root) {
if (root == null)
return new ArrayList<>();
List<Integer> ans = new ArrayList<>();
Queue<TreeNode> q = new ArrayDeque<>(Arrays.asList(root));
while (!q.isEmpty()) {
int max = Integer.MIN_VALUE;
for (int sz = q.size(); sz > 0; --sz) {
TreeNode node = q.poll();
max = Math.max(max, node.val);
if (node.left != null)
q.offer(node.left);
if (node.right != null)
q.offer(node.right);
}
ans.add(max);
}
return ans;
}
}
class Solution:
def largestValues(self, root: Optional[TreeNode]) -> List[int]:
if not root:
return []
ans = []
q = deque([root])
while q:
maxi = -math.inf
for _ in range(len(q)):
root = q.popleft()
maxi = max(maxi, root.val)
if root.left:
q.append(root.left)
if root.right:
q.append(root.right)
ans.append(maxi)
return ans