Python练习（一）

分别用for、while、递归求列表的和

>>> def list_sum(argument_list):
    sum = 0
    for arg in argument_list:
        sum += arg
    print('for =>',sum)

    sum = 0
    count = len(argument_list)
    while count > 0:
        sum += argument_list[count-1]
        count -= 1
    print('while =>',sum)
    
    def recursion_sum(arg_list):
        if len(arg_list) == 1:
            return     arg_list[0]
        else:
            return     arg_list[len(arg_list)-1] + recursion_sum(arg_list[:len(arg_list)-1])
    sum = recursion_sum(argument_list)
    print('recursion =>', sum)

    
>>> list_sum([1, 2, 3, 4, 5])
for => 15
while => 15
recursion => 15

交错合并列表函数

>>> def interlaced_combination_fun(a_list, b_list):
    result = [];
    for i in range(min(len(a_list), len(b_list))):
        if i < len(a_list):
            result.append(a_list[i])
        if i < len(b_list):
            result.append(b_list[i])
    print(result)

    
>>> interlaced_combination_fun([1, 3, 5, 7, 9], [2, 4, 6, 8])
[1, 2, 3, 4, 5, 6, 7, 8]

 给定非负整数列表中数字排列成最大数字

>>> def from_list_get_maxnum(arg_list):
    for i in range(len(arg_list)):
        for j in range(i):
            for k in range(min(arg_list[i]//10+1, arg_list[j]//10+1)):
                if int(str(arg_list[j])[k]) < int(str(arg_list[i])[k]):
                    arg_list[j], arg_list[i] =  arg_list[i],  arg_list[j]
                    break
    result = ''
    for arg in arg_list:
        result = result + str(arg)
    result = int(result)
    return result

>>> from_list_get_maxnum([50, 2, 1, 9])
95021

计算前100位的斐波那契函数

>>> def fibonacci(x):
    a, b = 0, 1
    print(a, end=' ')
    while 1:
        if a+b > 100:
            break
        a, b = b, a+b
        print(b, end = ' ')

        
>>> fibonacci(100)
0 1 2 3 5 8 13 21 34 55 89 

123456789顺序不能变，数字之间插入加减或什么都不插入，使结果总在100，输出所有可能性

>>> def fun(numbers, build):
    if(numbers):
        for char in ["+","","-"]:
            tmp = build + char + numbers[0]
            fun(numbers[1:], tmp)
    elif(eval(build) == 100):
        print(build)

        
>>> fun("23456789","1")
1+2+34-5+67-8+9
1+2+3-4+5+6+78+9
1+23-4+5+6+78-9
1+23-4+56+7+8+9
12+3+4+5-6-7+89
12+3-4+5+67+8+9
123+45-67+8-9
123+4-5+67-89
123-45-67+89
123-4-5-6-7+8-9
12-3-4+5-6+7+89