题解 | #把二叉树打印成多行#

• 层序遍历
• 记录每一层的数值；
• 返回最终结果。

/*
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
    TreeNode(int x) :
            val(x), left(NULL), right(NULL) {
    }
};
*/
class Solution {
public:
        vector<vector<int> > Print(TreeNode* pRoot) {
            vector<vector<int>> result;
            queue<TreeNode*> que;
            if (pRoot != NULL) que.push(pRoot);
            while (!que.empty()) {
                int size = que.size();
                vector<int> vec;
                for (int i = 0; i < size; i++) {
                    TreeNode* node = que.front();
                    que.pop();
                    vec.push_back(node->val);
                    if (node->left) que.push(node->left);
                    if (node->right) que.push(node->right);
                }
                result.push_back(vec);
            }
            return result;
        }
    
};