对两个列表合成一个列表后进行排序

lst1 = [2, 5, 7]
lst2 = [2, 4, 9, 0]
lst3 = lst1 + lst2
print(lst3)  # [2, 5, 7, 2, 4, 9, 0]
# print(sorted(lst1+lst2))
lst4 = []
i = 0  # 索引
min = lst3[0]  # 2

while len(lst3) > 0:      # i:    0  1  2  3  4  5  6  7
    if lst3[i] < min:  # lst[i]:  2  5  7  2  4  9  0
        min = lst3[i]     # min:  2  2  2  2  2  2  0  2
    i += 1                # len():7
    if i == len(lst3):    # lst4:                      [0]
                          # lst3:[2, 5, 7, 2, 4, 9]
        lst4.append(min)
        lst3.remove(min)
        if lst3:
            min = lst3[0]
        i = 0

print(lst4)