题解 | #求二叉树的层序遍历#

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

class Solution {
public:
    /**
     * 
     * @param root TreeNode类 
     * @return int整型vector<vector<>>
     */
    vector<vector<int> > levelOrder(TreeNode* root) {
        vector<vector<int>> res;
        queue<TreeNode*> q;
        if(!root)
            return {};
        q.push(root);
        while(!q.empty()){
            vector<int> out;
            for(int i=q.size(); i>0; i--){
                TreeNode* t = q.front();
                out.push_back(t->val);
                q.pop();
                if(t->left)
                    q.push(t->left);
                if(t->right)
                    q.push(t->right);
            }
            res.push_back(out);
        }
        return res;
        // write code here
    }
};