标签：
Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST.
According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes v and w as the lowest node in T that has both v and w as descendants (where we allow a node to be a descendant of itself).”
_______6______ / __2__ ___8__ / \ / \ 0 4 7 9 / 3 5
For example, the lowest common ancestor (LCA) of nodes 2 and 8 is 6. Another example is LCA of nodes 2 and 4 is 2, since a node can be a descendant of itself according to the LCA definition.
Subscribe to see which companies asked this question
Tags： Tree
Similar Problems： (M) Lowest Common Ancestor of a Binary Tree
class Solution { public: TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) { if (root == NULL || p == NULL || q == NULL) { return NULL; } std::stack<TreeNode *> staPath_p; std::stack<TreeNode *> staPath_q; GetBinaryTreePath(root, p, staPath_p); GetBinaryTreePath(root, q, staPath_q); int pSize = staPath_p.size(); int qSize = staPath_q.size(); if (pSize > qSize) { for (int i=0; i<pSize-qSize; i++) { staPath_p.pop(); } } else { for (int i=0; i<qSize-pSize; i++) { staPath_q.pop(); } } while (staPath_p.top() != staPath_q.top()) { staPath_p.pop(); staPath_q.pop(); } return staPath_p.top(); } private: bool GetBinaryTreePath(TreeNode* root, TreeNode* pDesNode, std::stack<TreeNode *> &staPath) { bool bIsFind = false; staPath.push(root); if (root == pDesNode) { return true; } if (NULL == staPath.top()->left && NULL == staPath.top()->right) { staPath.pop(); return false; } if (NULL != root->left) { bIsFind = GetBinaryTreePath(root->left, pDesNode, staPath); } if ( NULL != root->right && !bIsFind) { bIsFind = GetBinaryTreePath(root->right, pDesNode, staPath); } if (false == bIsFind) { staPath.pop(); return false; } else { return true; } } };
235. Lowest Common Ancestor of a Binary Search Tree
标签：
原文地址：http://www.cnblogs.com/whl2012/p/5778143.html
