Added solution

Author: avidLearnerInProgress

longest_palindromic_subsequence.cpp

@@ -0,0 +1,26 @@
+class Solution {
+public:
+    int longestPalindromeSubseq(string s) {
+        
+        if(s == "") return 0;
+        vector<vector<int>> dp(s.size(), vector<int>(s.size(), 0));
+        
+        for(int i=0; i<s.size(); i++){
+            dp[i][i] = 1;
+        }
+        
+        for(int i=s.size() - 1; i>=0; i--){
+            for(int j=i+1; j<s.size(); j++){
+              //      cout<<"i : j => "<<i<<j<<"\t";
+                
+                if(s[i] == s[j])
+                    dp[i][j] = dp[i+1][j-1] + 2;
+                else
+                    dp[i][j] = max(dp[i+1][j], dp[i][j-1]);
+            }
+            //cout<<"\n";
+            
+        }
+        return dp[0][s.size() - 1];
+    }
+};

search_in_bst.cpp

@@ -0,0 +1,28 @@
+/**
+ * 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* helper(TreeNode* root, int val){
+        if(root == NULL) return root;
+        
+        if(root->val == val) return root;
+        else if(root->val < val) return helper(root->right, val);
+        else return helper(root->left,val);
+        
+        return NULL;
+    }
+    
+    TreeNode* searchBST(TreeNode* root, int val) {
+        
+        if(root == NULL) return root;
+        return helper(root, val); 
+    }
+};