add python code

public/py/ch2/quicksort/quicksort.py

@@ -0,0 +1,33 @@
+"""
+快速排序 — 分治策略
+平均时间复杂度 O(n log n)，最坏 O(n²)
+"""
+
+def partition(arr, low, high):
+    """划分：选择基准，将小于基准的放左边，大于的放右边"""
+    pivot = arr[high]  # 选最后一个元素作为基准
+    i = low - 1
+
+    for j in range(low, high):
+        if arr[j] <= pivot:
+            i += 1
+            arr[i], arr[j] = arr[j], arr[i]
+
+    arr[i + 1], arr[high] = arr[high], arr[i + 1]
+    return i + 1
+
+def quick_sort(arr, low, high):
+    """快速排序递归实现"""
+    if low < high:
+        pi = partition(arr, low, high)
+        quick_sort(arr, low, pi - 1)
+        quick_sort(arr, pi + 1, high)
+
+def sort(arr):
+    quick_sort(arr, 0, len(arr) - 1)
+
+if __name__ == "__main__":
+    data = [10, 7, 8, 9, 1, 5]
+    print("排序前:", data)
+    sort(data)
+    print("排序后:", data)