Binary Tree Level Order Traversal
Difficulty: MediumTopic: TreeBreadth-First SearchBinary TreeLeetcode:102.Binary Tree Level Order TraversalGiven the root of a binary tree, return the level order traversal of its nodes' values. (i.e., from left to right, level by level).
Example 1:
Input: root = [3,9,20,null,null,15,7]
Output: [[3],[9,20],[15,7]]
Example 2:
Input: root = [1]
Output: [[1]]
Example 3:
Input: root = []
Output: []
Constraints:
- The number of nodes in the tree is in the range
[0, 2000]. -1000 <= Node.val <= 1000
Solution
write solution in here
/**
* @param {TreeNode} root
* @return {number[][]}
*/
var levelOrder = function(root) {
if (!root) return []
const queue = [root], res = []
while(queue.length) {
const len = queue.length,
cur = []
for(let i = 0; i < len; i ++) {
const curr = queue.shift()
cur.push(curr.val)
curr.left && queue.push(curr.left)
curr.right && queue.push(curr.right)
}
res.push(cur)
}
return res
};