从零开始Leetcode – Day 10
##Binary Tree Level Order Traversal
不是很熟悉 curNum, lastNum. 理解得不够透彻。早点休息， 明天再努力。
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* @param {TreeNode} root
* @return {number[][]}
*/
var levelOrder = function(root) {
var queue = [];
var list = [];
var res = [];
if(!root){
return res;
}
queue.push(root);
curNum = 0;
lastNum =1;
while(queue.length){
var cur = queue.shift();
list.push(cur.val);
lastNum--;
if(cur.left){
curNum++;
queue.push(cur.left);
}
if(cur.right){
curNum++;
queue.push(cur.right);
}
if(lastNum ===0){
lastNum = curNum;
curNum = 0;
res.push(list);
list = [];
}
}
return res;
};
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