找树左下角的值（递归，迭代）JAVA！

// 递归法
class Solution {
    private int Deep = -1;
    private int value = 0;
    public int findBottomLeftValue(TreeNode root) {
        value = root.val;
        findLeftValue(root,0);
        return value;
    }

    private void findLeftValue (TreeNode root,int deep) {
        if (root == null) return;
        if (root.left == null && root.right == null) {
            if (deep > Deep) {
                value = root.val;
                Deep = deep;
            }
        }
        if (root.left != null) findLeftValue(root.left,deep + 1);
        if (root.right != null) findLeftValue(root.right,deep + 1);
    }
}

//迭代法
class Solution {

    public int findBottomLeftValue(TreeNode root) {
        Queue<TreeNode> queue = new LinkedList<>();
        queue.offer(root);
        int res = 0;
        while (!queue.isEmpty()) {
            int size = queue.size();
            for (int i = 0; i < size; i++) {
                TreeNode poll = queue.poll();
                if (i == 0) {
                    res = poll.val;
                }
                if (poll.left != null) {
                    queue.offer(poll.left);
                }
                if (poll.right != null) {
                    queue.offer(poll.right);
                }
            }
        }
        return res;
    }
}

标签：poll,JAVA,int,找树,queue,right,左下角,null,root
来源： https://blog.csdn.net/weixin_43297708/article/details/120790613