题解 | #求二叉树的层序遍历#

/**
 * struct TreeNode {
 *	int val;
 *	struct TreeNode *left;
 *	struct TreeNode *right;
 * };
 */

#include <iterator>
#include <vector>
class Solution {
public:
    /**
     * 
     * @param root TreeNode类 
     * @return int整型vector<vector<>>
     */
    vector<vector<int> > levelOrder(TreeNode* root) {
        vector<vector<int>> ans;
        if(root==nullptr) return ans ;
        queue<TreeNode*> Q;
        Q.push(root);
        vector<int>t;
        while(!empty(Q)){
            int size=Q.size();
            while(size--){
                root=Q.front();
                Q.pop();
                t.push_back(root->val);
                if(root->left) Q.push(root->left);
                if(root->right) Q.push(root->right);
            }
            ans.push_back(t);
            t.clear();
        }
        return ans;
    }
};