Merge pull request #487 from sumiranverma/patch-9

Create question.md

Day-22/q2: Sum of Left Leaves/question.md

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+Given the `root` of a binary tree, return the sum of all left leaves.
+
+A **leaf** is a node with no children. 
+A **left leaf** is a leaf that is the left child of another node.
+
+### **_Example 1_**
+
+![image](https://github.com/SnowScriptWinterOfCode/LeetCode_Q/assets/112773734/82f26aff-30a7-4d6e-91ad-dd0cdc562ff6)
+
+**Input**: root = [3,9,20,null,null,15,7]
+**Output**: 24
+**Explanation**: There are two left leaves in the binary tree, with values 9 and 15 respectively.
+
+### **_Example 2_**
+
+**Input**: root = [1]
+**Output**: 0
+
+
+### Constraints:
+
+- The number of nodes in the tree is in the range `[1, 1000]`.
+- `1000` <= Node.val <= `1000`
+
+### problem link: 
+https://leetcode.com/problems/sum-of-left-leaves/