Add solution for deepest leaves sum leetcode problem

Author: samkit96

leetcode/cpp/Tree/1302.cpp

@@ -0,0 +1,58 @@
+/**
+ * Problem link: https://leetcode.com/problems/deepest-leaves-sum/
+ * Solution:
+ * (1) If the current leaf node depth is greater than the maximum leaf depth found till now, set maximum depth as current leaf depth and initialize sum.
+ * (2) If the current leaf node depth is less than the maximum leaf depth found till now, dont do anything.
+ * (3) If the current leaf node depth is equal to the maximum leaf depth found till now, increase the sum.
+ *
+ * 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:
+    
+    int mx_d, ans;
+    
+    void dfs(TreeNode *node, int depth) {
+        
+        if (node == NULL) return;
+        
+        if (node->right == NULL && node->left == NULL) {
+            
+            if (depth == mx_d) {
+                
+                ans += node->val;
+                
+            } else if (depth > mx_d) {
+                
+                mx_d = depth;
+                ans = node->val;
+                
+            } else if (depth < mx_d) {
+                
+                return;
+            }
+        }
+        
+        if (node->right != NULL) dfs(node->right, depth+1);
+        
+        if (node->left != NULL) dfs(node->left, depth+1);
+    }
+    
+    int deepestLeavesSum(TreeNode* root) {
+        
+        mx_d = 0;
+        ans = 0;
+        
+        dfs(root, 0);
+        
+        return ans;
+    }
+};