Leetcode 235. Lowest Common Ancestor of a Binary Search Tree (Easy) (cpp)

Leetcode 235. Lowest Common Ancestor of a Binary Search Tree (Easy) (cpp)

Tag: Tree

Difficulty: Easy

/*235. Lowest Common Ancestor of a Binary Search Tree (Easy)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   5For 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.*//** * Definition for a binary tree node. * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */ class Solution { public: TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) { if (min(p -> val, q -> val) < root -> val && max(p -> val, q -> val) > root -> val) return root; else if (root -> val < min(p -> val, q -> val)) return lowestCommonAncestor(root -> right, p, q); else if (root -> val > max(p -> val, q -> val)) return lowestCommonAncestor(root -> left, p, q); else return root; } };