LeetCode 103. 二叉树的锯齿形层序遍历

LeetCode 103. 二叉树的锯齿形层序遍历

思路：
根下面这道题一样，就是把res中奇数的vector反转
参考

代码：

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    vector<vector<int>> zigzagLevelOrder(TreeNode* root) {
        //跟上一个题一样，把res中奇数vector反转
        vector<vector<int>> res;
        queue<TreeNode*> q;
        if(root) q.push(root);

        while(q.size()){
            int len=q.size();
            vector<int> level;
            while(len--){
                auto t = q.front();
                q.pop();
                level.push_back(t->val);
                if(t->left) q.push(t->left);
                if(t->right) q.push(t->right);
            }
            res.push_back(level);
        }
        for(int i=0;i<res.size();i++){
            if(i%2){
                reverse(res[i].begin(),res[i].end());
            }
        }
        return res;
    }
};