题解 | #二叉树的最大深度#

// 层次遍历
function maxDepth( root ) {
    // write code here
    //深度
   let depth = 0
   //判空
   if(!root) return depth
   if(!root.left&&!root.right) return 1
    //保存当前层节点
   let current = []
   //保存下一层层节点
   let next = []
   current.push(root)
   while(current.length||next.length){
       while(current.length){
//         添加一个节点的左右孩子后就将其弹出
           if(current[0].left) next.push(current[0].left)
           if(current[0].right) next.push(current[0].right)
           current.shift()
       }
//        current为空，说明当前层遍历完
       depth++
       current = next
       next = []
   }
   return depth
    
}