题解 | #求二叉树的层序遍历#

/**
 * struct TreeNode {
 *  int val;
 *  struct TreeNode *left;
 *  struct TreeNode *right;
 *  TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 * };
 */
#include <queue>
class Solution {
  public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param root TreeNode类
     * @return int整型vector<vector<>>
     */
    vector<vector<int> > levelOrder(TreeNode* root) {
        // write code here
        vector<vector<int> >res;
        queue<TreeNode*> t;
        if(root)t.push(root);
        while(!t.empty()) {       
            auto t1 =new queue<TreeNode*>();
            auto r = new vector<int>();
            while (!t.empty()) {
                TreeNode* f = t.front();
                if(f->left)t1->push(f->left);
                if(f->right)t1->push(f->right);
                r->push_back(f->val);
                t.pop();
            }
            res.push_back(*r);
            t=*t1;

        }

        return res;
    }
};