🔥 Day 8

Author: AkashRajpurohit

README.md

@@ -4,7 +4,7 @@
 
 [Challenge Link](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge/)
 
-## Week 1 🚧
+## Week 1 ✅
 1. [Detect Capital](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge/549/week-1-august-1st-august-7th/3409/) ➡️ [CPP Solution](Week1/detectCapital.cpp)
 2. [Design HashSet](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge/549/week-1-august-1st-august-7th/3410/) ➡️ [CPP Solution](Week1/designHashset.cpp)
 3. [Valid Palindrome](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge/549/week-1-august-1st-august-7th/3411/) ➡️ [CPP Solution](Week1/validPalindrome.cpp)
@@ -13,6 +13,9 @@
 6. [Find All Duplicates in an Array](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge/549/week-1-august-1st-august-7th/3414/) ➡️ [CPP Solution](Week1/findDuplicates.cpp)
 7. [Vertical Order Traversal of a Binary Tree](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge/549/week-1-august-1st-august-7th/3415/) ➡️ [CPP Solution](Week1/verticalTraversal.cpp)
 
+## Week 2 🚧
+1. [Path Sum III](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge/550/week-2-august-8th-august-14th/3417/) ➡️ [CPP Solution](Week2/pathSum.cpp)
+
 ## Where to find me? 🌟
 * [Website](https://akashwho.codes/)
 * [Linkedin](https://www.linkedin.com/in/AkashRajpurohit)

Week2/pathSum.cpp

@@ -0,0 +1,34 @@
+/**
+ * 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 {
+    int pathSumHelper(TreeNode* root, int currSum, int target, unordered_map<int, int>& preSum) {
+        if(root == NULL) return 0;
+        
+        currSum += root->val;
+        
+        int res = preSum[currSum - target];
+        
+        preSum[currSum]++;
+        
+        res += pathSumHelper(root->left, currSum, target, preSum) + pathSumHelper(root->right, currSum, target, preSum);
+        
+        preSum[currSum]--;
+        
+        return res;
+    }
+public:
+    int pathSum(TreeNode* root, int sum) {
+        unordered_map<int, int> preSum;
+        preSum[0] = 1;
+        return pathSumHelper(root, 0, sum, preSum);
+    }
+};