差两题，待更新

513. 找树左下角的值

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number}
 */
var findBottomLeftValue = function(root) {
    const queue = [];
    if (root) queue.push(root);
    let res = 0;
    while (queue.length) {
        let size = queue.length;
        for (let i = 0; i < size; i++) {
            const node = queue.shift();
            if (i === 0) res = node.val 
            node.left && queue.push(node.left);
            node.right && queue.push(node.right);
        }
    }
    return res;
};