Leetcode_107_binary Tree level Order traversal II

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107 Binary Tree level Order traversal II

Given a binary tree, return the bottom-up level order traversal of its nodes ' values. (ie, from the left-to-right, the level by level from the leaf to root).

For example:
Given binary Tree {3,9,20,#,#,15,7},
3
/ \
9 20
/  \
15 7
Return its bottom-up level order traversal as:
[
[15,7],
[9,20],
[3]
]

/** * Definition for binary tree * struct TreeNode {* int val; * TreeNode *left; * TreeNode *right; * Tre Enode (int x): Val (x), left (null), right (NULL) {} *};  *///Method One: bfsstruct node{TreeNode *node;  int level; Node (TreeNode *n, int L): node (n), level (L) {}};class solution {vector<vector<int>> ANS;PUBLIC:VECTOR&L        t;vector<int> > Levelorderbottom (TreeNode *root) {ans.clear ();                if (root = NULL) return ans;        Vector<int> temp;                int curlevel =-1;        Queue<node> Q;                Q.push (Node (root, 1));            while (!q.empty ()) {Node Nodeq = Q.front ();                        Q.pop ();            if (nodeq.node->left) Q.push (node (nodeq.node->left, nodeq.level+1));                        if (nodeq.node->right) Q.push (node (nodeq.node->right, nodeq.level+1));    if (curlevel! = nodeq.level) {            if (curlevel! =-1) ans.push_back (temp);                Temp.clear ();                Temp.push_back (Nodeq.node->val);            Curlevel = Nodeq.level;        } else Temp.push_back (Nodeq.node->val);                } ans.push_back (temp);        Reverse (Ans.begin (), Ans.end ());    return ans; }};

Method Two: Dfsclass solution {vector<vector<int>> ans;public:    void Levelorderutil (TreeNode *root, int Depth)    {        if (root==null)            return;        if (Ans.size () > Depth)            ans[depth].push_back (root->val);        else        {            vector<int> A;            A.push_back (root->val);            Ans.push_back (a);        }        Levelorderutil (Root->left, depth+1);        Levelorderutil (Root->right, depth+1);    }        vector<vector<int> > Levelorderbottom (TreeNode *root) {        ans.clear ();        Levelorderutil (root, 0);        Reverse (Ans.begin (), Ans.end ());        return ans;    };

Leetcode_107_binary Tree level Order traversal II