513. 找树左下角的值

题目链接

/**
 * @param {TreeNode} root
 * @return {number}
 */
var findBottomLeftValue = function(root) {
    if (!root) return null;
    const queue = [root];
    let leftVal = root?.val;
    while(queue.length) {
        const levelLen = queue.length;
        for(let i=0; i<levelLen; i++) {
            const curNode = queue.pop();
            if(i === 0) leftVal = curNode.val;
            if (curNode.left) queue.unshift(curNode.left);
            if (curNode.right) queue.unshift(curNode.right);
        }
    }
    return leftVal;
};