def selection_sort(arr):"""选择排序:param arr: 待排序数组:return:"""length = len(arr)for x in range(length):min_index = x# 选取最小的下标for y in range(x + 1, length):if arr[min_index] > arr[y]:min_index = y# 交换arr[x], arr[min_index] = arr[min_index], arr[x]if __name__ == '__main__':arr = [20, -1, 2, 11, 8, 100, 4, 10, 23, 6, 21]selection_sort(arr)print(arr)