[다시풀기/릿코드/javascript] 102. Binary Tree Level Order Traversal

var levelOrder = function(root) {
    //BFS하라는 뜻인듯...????
    let output = [];
    let queue = [root];
    if(!root) return output;
    while(queue.length){
        let answer = []
        let len = queue.length
        for(let i=0;i<len;i++){
        let current = queue.shift();
        answer.push(current.val)
        if(current.left) queue.push(current.left)
        if(current.right) queue.push(current.right)
        }
        output.push(answer)
    }
    return output
};