[Leetcode] Kth smallest Element in a BST

This link suggests a concise C + + recursive solution. The original code may is hard-understand at first and I have rewritten the code below. Need to run some examples and it to see how it works.

1 classSolution {2  Public:3     intKthsmallest (treenode* root,intk) {4         returnsmallest (root, k);5     }6 Private:7     intSmallest (treenode* node,int&k) {8         if(!node)return-1;9         intval = Smallest (node-Left , k);Ten         if(!k)returnVal; One         if(!--k)returnNode-Val; A         returnSmallest (node-Right , k); -     } -};

The same author also posts three solutions which is more space-efficient in this link. All of them reduce the o (n) space of the above code to O (k) space by using some nice data structures.

Personally I really love the soltuion using deque and I had rewritten it below.

1 classSolution {2  Public:3     intKthsmallest (treenode* root,intk) {4treenode* node =Root;5Deque<treenode*>nodes;6          while(true) {7              while(node) {8 Nodes.push_front (node);9                 if(Nodes.size () >k)Ten Nodes.pop_back (); Onenode = nodeLeft ; A             } -node =Nodes.front (); - Nodes.pop_front (); the             if(!--k)returnNode-Val; -node = nodeRight ; -         } -     } +};

[Leetcode] Kth smallest Element in a BST