day22-q2 solution added in python, java #464

Day-22/q2: Sum of Left Leaves/Tech-neophyte--pj.md

@@ -0,0 +1,38 @@
+## Python code: Iterative DFS using Stack
+```
+class Solution(object):
+    def sumOfLeftLeaves(self, root):
+        """
+        :type root: TreeNode
+        :rtype: int
+        """
+        if not root:
+            return 0
+        stack = [root]
+        res = 0
+        while stack:
+            u = stack.pop()
+            if u.left:
+                stack.append(u.left)
+                if not u.left.left and not u.left.right:
+                    res += u.left.val
+            if u.right:
+                stack.append(u.right)
+        return res
+```
+## Java code:
+```
+class Solution {
+    public int sumOfLeftLeaves(TreeNode root) {
+        if (root == null) {
+            return 0;
+        }
+
+        int sum = 0;
+        if (root.left != null && root.left.left == null && root.left.right == null) {
+            sum += root.left.val;
+        }
+        return sumOfLeftLeaves(root.left) + sumOfLeftLeaves(root.right) + sum;
+    }
+}
+```