Create Solution2.cpp

Author: AlleyNawaz

solution/0400-0499/0404.Sum of Left Leaves/Solution2.cpp

@@ -0,0 +1,27 @@
+//Approach 2: Iterative
+//Time: O(n)
+//Space: O(h)
+class Solution {
+ public:
+  int sumOfLeftLeaves(TreeNode* root) {
+    if (root == nullptr)
+      return 0;
+
+    int ans = 0;
+    stack<TreeNode*> stack{{root}};
+
+    while (!stack.empty()) {
+      root = stack.top(), stack.pop();
+      if (root->left) {
+        if (root->left->left == nullptr && root->left->right == nullptr)
+          ans += root->left->val;
+        else
+          stack.push(root->left);
+      }
+      if (root->right)
+        stack.push(root->right);
+    }
+
+    return ans;
+  }
+};