Python学习笔记-初级（三）：数据结构

一、问题背景

“Python语言导论“课程作业。

二、实现环境

Windows 8， Python 3.5 IDLE

三、题目

1、 输出1~100之间不能被7整除的数，每行输出10个数字，要求应用字符串对齐函数美化输出格式。

（1）代码

'''Author: WJTDate: 24/10/2016function: output all the numbers can't be divided bynumbers between 1 and 100'''count = 0for i in range(1, 101):        if (i % 7 != 0):                print("% 4d" % i, end=' ')                count += 1                if (count%10 == 0):                        print('\n')

（2）运行结果

2、假定s是小写字母的字符串。编写程序，输出s的最长子串（子串必须是字母顺序）。

如：s = 'azcbobobegghakl'，则应输出：

Longestsubstring in alphabetical order is: beggh

又如：s = 'abcbcd'，则应输出第一个子串：

Longestsubstring in alphabetical order is: abc

 

（1）代码

'''Author: WJTDate: 10/24/2016function: output longest substring in alphabetical order''''''# this version of imeplemention is of low efficiencydef longest_sub(string):        # each character is a substring of length 1        length=[]        for i in range(0, len(string)):                length.append(1)        for i in range(0, len(string)-1):                for j in range(i, len(string)-1):                        if (string[j] <= string[j+1]):                                length[i] += 1                        else:                                break        max_length = max(length)        max_index = length.index(max_length)        # for debug        #print(length)        #print(max_length, max_index)        print("Longest substring in alphabetetic order is: ", end=' ')        for i in range(max_index, max_index + max_length):                print(string[i], end='')        print('\n')'''# another version of implementiondef longest_sub(string):    i = 0    max_length = 1    temp_length = 1    while(i < len(string) - 1):        if(string[i] <= string[i + 1]):            temp_length += 1            if(temp_length > max_length):                max_length = temp_length                # record the index of the last element in longest sub-string                max_index = i + 1                              else:            temp_length = 1        i += 1            # for debug    #print(max_length, max_index)    print("Longest substring in alphabetetic order is: ", end=' ')    for i in range(max_index - max_length + 1, max_index + 1):        print(string[i], end='')    print('\n')# testbenchs = 'azcbobobegghakl'longest_sub(s)s = 'abcbcd'longest_sub(s)

（2）运行结果

3、 假定n1和n2为正整数，编写函数：findDivisors(n1, n2)，返回包含n1、n2公因子的元组。

 （1）代码

'''Author: WJTDate: 24/10/2016function: return the tuple whose elements are common divisors of n1 and n2'''def findDivisors(n1, n2):    return_tuple = ( )    if (n1 < n2):        min_num = n1        max_num = n2    else:        min_num = n2        max_num = n1    for i in range(1, min_num):        if ((min_num % i == 0) and (max_num % i == 0)):            # add element to a tuple            return_tuple = return_tuple + (i,)    return return_tuple

（2）运行结果

4、假定已经执行了以下语句序列：

animals = { 'a': ['aardvark'], 'b': ['baboon'], 'c':['coati']}   #值都是列表

animals['d'] = ['donkey']

animals['d'].append('dog')

animals['d'].append('dingo')

编写函数：bigest(Dict)，返回其值包含元素个数最多的键值。

（1）代码

'''Author: WJTDate: 10/24/2016Function: return the key of the dictionary value which has the most elements'''def biggest(Dict):    max_len = 0    for k in Dict.keys():        if (max_len < len(Dict[k])):            max_len = len(Dict[k])            max_len_key = k    print(max_len_key)    #return max_len_key# testbenchanimals = { 'a': ['aardvark'], 'b': ['baboon'], 'c': ['coati']}   #值都是列表animals['d'] = ['donkey']animals['d'].append('dog')animals['d'].append('dingo')biggest(animals)biggest({'a': [3, 3, 18], 'c': [3, 15, 12, 10, 0], \         'b': [10, 19, 14, 5, 16, 20, 11, 6], \         'd': [5, 16, 8, 16, 6, 1]})

（2）运行结果