Update and rename path_sum_2.cpp to path_sum_ii.cpp

Author: avidLearnerInProgress

path_sum_2.cpp

@@ -0,0 +1,48 @@
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
+ * };
+ */
+class Solution {
+public:
+    //final ds
+    vector<vector<int>> result;
+    
+    //intermediary ds to check if current path is a 'path sum'
+    vector<int> current_path; 
+        
+    //recursive method to find all root-to-leaf paths
+    void helper(TreeNode* root, int sum) {
+        
+        
+        //base case i
+        if(!root) return;
+        
+        current_path.push_back(root->val); //push current node in path and recurse for all the children emanting out of the path from current node i.e. root
+        
+        //basecase ii
+        if(!root->left && !root->right && root->val == sum) {
+            result.push_back(current_path);
+        }
+        
+        else { //recurse for child nodes
+            sum -= root->val;
+            helper(root->left, sum);
+            helper(root->right, sum);
+        }
+        
+        current_path.pop_back(); //remove current visited node
+    }
+    
+    vector<vector<int>> pathSum(TreeNode* root, int sum) {
+        if(!root) return vector<vector<int>> ();
+        helper(root, sum);
+        return result;
+    }
+};