diff --git "a/leetcode3/\354\265\234\354\233\220\354\244\200/315. Count of Smaller Numbers After Self.py" "b/leetcode3/\354\265\234\354\233\220\354\244\200/315. Count of Smaller Numbers After Self.py"
new file mode 100644
index 00000000..4b5e6bc2
--- /dev/null
+++ "b/leetcode3/\354\265\234\354\233\220\354\244\200/315. Count of Smaller Numbers After Self.py"	
@@ -0,0 +1,46 @@
+class Solution:
+    def countSmaller(self, nums: List[int]) -> List[int]:
+        n = len(nums)
+        ans = [0] * n
+
+        arr = [(num, i) for i, num in enumerate(nums)]
+
+        def merge_sort(arr):
+            if len(arr) <= 1:
+                return arr
+
+            mid = len(arr) // 2
+
+            left = merge_sort(arr[:mid])
+            right = merge_sort(arr[mid:])
+
+            merged = []
+
+            i = 0
+            j = 0
+            smaller = 0
+
+            while i < len(left) and j < len(right):
+                if left[i][0] <= right[j][0]:
+                    ans[left[i][1]] += smaller
+                    merged.append(left[i])
+                    i += 1
+                else:
+                    smaller += 1
+                    merged.append(right[j])
+                    j += 1
+
+            while i < len(left):
+                ans[left[i][1]] += smaller
+                merged.append(left[i])
+                i += 1
+
+            while j < len(right):
+                merged.append(right[j])
+                j += 1
+
+            return merged
+
+        merge_sort(arr)
+
+        return ans