使用嵌套while循環的冰雹序列

Question

我正在編寫一個程序，該程序允許用戶輸入一定范圍的數字，然后該程序將對該范圍內的每個數字進行一次冰雹序列處理，然后將打印出最大循環長度的數字。 我看不到為什么我的代碼無法正常工作。 我們需要使用while循環

def main():
    #set starting variables
    start_num = int(input('Enter starting number of the range: '))
    #check if the numbers entered are positive and that the start is less than the end
    while (start_num < 1):
            start_num = int(input('Enter a positive starting number of the range: '))
    end_num = int(input('Enter ending number of the range: '))
    while (end_num < 1):
            end_num = int(input('Enter a positive ending number of the range: '))

    while (start_num > end_num):
            start_num = int(input('Enter starting number of the range: '))
            end_num = int(input('Enter ending number of the range: '))

    cycle_length = 0
    max_length = 0
    num_max = 0
    num = 0

    while (start_num < end_num):

            while (num != 1):

                    if (start_num % 2 == 0):
                            num = start_num / 2
                            cycle_length = cycle_length +1
                    else:
                            num = (start_num * 3) + 1
                            cycle_length = cycle_length +1      

                    if (cycle_length >= max_length):
                            max_length = cycle_length
                            num_max = start_num

                    cycle_length = 0
            start_num = start_num + 1

    print(num_max)
    print(max_length)

main()

Answer 1

在while循環中，您始終在檢查start_num ，它永遠不會改變。 在循環的最開始，您需要將num設置為start_num 。 然后在整個循環體內使用num 。

Answer 2

我將仔細檢查每一行，並告訴您問題所在。 您應該真正確保知道每個變量持有什么以及應該持有什么。

def main():
    #set starting variables
    start_num = int(input('Enter starting number of the range: '))
    #check if the numbers entered are positive and that the start is less than the end
    while (start_num < 1):
            start_num = int(input('Enter a positive starting number of the range: '))
    end_num = int(input('Enter ending number of the range: '))
    while (end_num < 1):
            end_num = int(input('Enter a positive ending number of the range: '))

    while (start_num > end_num):
            start_num = int(input('Enter starting number of the range: '))
            end_num = int(input('Enter ending number of the range: '))

    cycle_length = 0
    max_length = 0
    num_max = 0
    num = 0

    while (start_num < end_num):

start_num和end_num不會改變，因此您有一個無限循環，例如while（10 <100）

            while (num != 1):

num當前為0，因為幾行前將其設置為0后尚未將其分配給任何內容

                    if (start_num % 2 == 0):
                            num = start_num / 2

num現在是start_num/2 ，但start_num永不更改

                            cycle_length = cycle_length +1
                    else:
                            num = (start_num * 3) + 1

同樣在這里

                            cycle_length = cycle_length +1      

                    if (cycle_length >= max_length):
                            max_length = cycle_length
                            num_max = start_num

您正在將num_max設置為start_num但是start_num永不更改

                    cycle_length = 0

您正在每個周期重置cycle_num

            start_num = start_num + 1
     print(num_max)
     print(max_length)

main()