Create solution.cpp

Author: wlgq2

235.cmmon_ancestor/solution.cpp

@@ -0,0 +1,30 @@
+class Solution 
+{
+public:
+    void  haveNode(TreeNode* node, TreeNode* p,TreeNode* q,TreeNode*& out)
+    {
+        if (node == NULL || out != NULL)
+            return;
+
+        if ((node->val >= q->val && node->val <= p->val) ||
+            (node->val <= q->val && node->val >= p->val))
+        {
+            out = node;
+        }
+        else if (node->val >= q->val && node->val >= p->val)
+        {
+            haveNode(node->left, p, q, out);
+        }
+        else if (node->val <= q->val && node->val <= p->val)
+        {
+            haveNode(node->right, p, q, out);
+        }
+    }
+
+    TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) 
+    {
+        TreeNode* node(NULL);
+        haveNode(root, p, q,node);
+        return node;
+    }
+};