Find Largest Value in Each Tree Row
给一个二叉树, 找每层最大的值. 直接层序扫描.
class Solution {
public List<Integer> largestValues(TreeNode root) {
List<Integer> res = new ArrayList<>();
if(root == null)
return res;
Queue<TreeNode> q = new LinkedList<>();
q.offer(root);
while(!q.isEmpty()) {
int size = q.size();
int max = Integer.MIN_VALUE;
for(int i = 0; i < size; i++) {
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);
}
res.add(max);
}
return res;
}
}