[LeetCode] Problem 513 - Find Bottom Left Tree Value

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Given a binary tree, find the leftmost value in the last row of the tree.

Example

No.1

Input:

1
2
3
  2
 / \
1   3

Output:
1

No.2

Input:

1
2
3
4
5
6
7
    1
   / \
  2   3
 /   / \
4   5   6
   /
  7

Output:
7

Note

You may assume the tree (i.e., the given root node) is not NULL.

Code

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public class TreeNode {
    int val;
    TreeNode left;
    TreeNode right;
    TreeNode(int x) { val = x; }
}
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public int findBottomLeftValue(TreeNode root) {
    int result = 0;
    Queue<TreeNode> queue = new LinkedList<>();
    queue.offer(root);

    while (!queue.isEmpty()) {
        int size = queue.size();

        for (int i = 0; i < size; i++) {
            TreeNode node = queue.poll();
            result = node.val;

            if (node.right != null)
                queue.offer(node.right);
            if (node.left != null)
                queue.offer(node.left);
        }
    }

    return result;
}