Add binary search to find peak index in a mountain array

data_structures/arrays/peak_mountain_array.py

@@ -0,0 +1,25 @@
+"""
+peak_mountain_array.py
+Author: Taha Zulfiquar
+Description: Finds the peak index in a mountain array using binary search.
+"""
+
+from typing import List
+
+
+def peak_mountain(arr: List[int]) -> int:
+    start, end = 0, len(arr) - 1
+
+    while start < end:
+        mid = start + (end - start) // 2
+        if arr[mid] > arr[mid + 1]:
+            end = mid
+        else:
+            start = mid + 1
+    return start
+
+
+if __name__ == "__main__":
+    arr = [1, 2, 3, 5, 7, 8, 6, 3, 2]
+    peak_index = peak_mountain(arr)
+    print(f"The peak index is: {peak_index}")