diff --git a/problems/0004-median-of-two-sorted-arrays/solution.py b/problems/0004-median-of-two-sorted-arrays/solution.py
new file mode 100644
index 0000000..91156a3
--- /dev/null
+++ b/problems/0004-median-of-two-sorted-arrays/solution.py
@@ -0,0 +1,24 @@
+class Solution:
+    def findMedianSortedArrays(self, nums1: list[int], nums2: list[int]) -> float:
+        if len(nums1) <= len(nums2):
+            A, B = nums1, nums2
+        else:
+            A, B = nums2, nums1
+        half_total = (len(A) + len(B)) // 2
+        lo, hi = 0, len(A)
+        while True:
+            i = (lo + hi) // 2
+            j = half_total - i
+            Aleft = A[i - 1] if i > 0 else float("-inf")
+            Aright = A[i] if i < len(A) else float("inf")
+            Bleft = B[j - 1] if j > 0 else float("-inf")
+            Bright = B[j] if j < len(B) else float("inf")
+            if Aleft > Bright:
+                hi = i - 1
+            elif Bleft > Aright:
+                lo = i + 1
+            else:
+                if (len(A) + len(B)) % 2 != 0:
+                    return min(Aright, Bright)
+                else:
+                    return (max(Aleft, Bleft) + min(Aright, Bright)) / 2
diff --git a/problems/0004-median-of-two-sorted-arrays/solution_test.py b/problems/0004-median-of-two-sorted-arrays/solution_test.py
new file mode 100644
index 0000000..6e00963
--- /dev/null
+++ b/problems/0004-median-of-two-sorted-arrays/solution_test.py
@@ -0,0 +1,13 @@
+import pytest
+from solution import Solution
+
+
+@pytest.mark.parametrize(
+    "nums1, nums2, expected",
+    [
+        ([1, 3], [2], 2),
+        ([1, 2], [3, 4], 2.5),
+    ],
+)
+def test_REPLACE(nums1, nums2, expected):
+    assert Solution().findMedianSortedArrays(nums1, nums2) == expected