The sword refers to OFFER---- print the binary tree into multiple lines

Topic description

Print the binary tree layer by layer from top to bottom, and the nodes in the same layer are output from left to right. Each layer outputs one line.

/*
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
    TreeNode(int x) :
            val(x), left(NULL), right(NULL) {
    }
};
*/
//loop solution

class Solution {
public:
        vector<vector<int> > Print(TreeNode* pRoot) {
            vector<vector<int>> v;
            if(pRoot == NULL)
                return v;
            queue<TreeNode *> qu;
            TreeNode * p = NULL;
            qu.push(pRoot);
            vector<int> t;int count = 0;
            while(!qu.empty()){
                count = qu.size();//Get the number of nodes in each layer
                while(count--){
                    p = qu.front();
                    t.push_back(p->val);
                    if(p->left)
                        qu.push(p->left);
                    if(p->right)
                        qu.push(p->right);
                    qu.pop();
                }
                v.push_back(t);
                t.clear();
            }
            return v;
        }
};

//Recursive writing, depth-first traversal. Use the depth of the stack and the height of the tree to compare
class Solution {
public:
        vector<vector<int> > Print(TreeNode* pRoot) {
            vector<vector<int>> v;
            if(pRoot == NULL)
                return v;
            dfs(pRoot,1,v);
            return v;
        }
        void dfs(TreeNode* root,int depth,vector<vector<int>> &v)
        {
            if(root == NULL)return ;
            if(depth > v.size())
                v.push_back(vector<int>());
            v[depth - 1].push_back(root->val);
            dfs(root->left,depth + 1, v);
            dfs(root->right,depth + 1, v);
        }
};