python面試的100題（13）

29.Given an array of integers

給定一個整數數組和一個目標值，找出數組中和爲目標值的兩個數。你能夠假設每一個輸入只對應一種答案，且一樣的元素不能被重複利用。示例:給定nums = [2,7,11,15],target=9 由於 nums[0]+nums[1] = 2+7 =9,因此返回[0,1]

class Solution:
    def twoSum(self,nums,target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: List[int]
        """
        d = {}
        size = 0
        while size < len(nums):
            if target-nums[size] in d:
                if d[target-nums[size]] <size:
                    return [d[target-nums[size]],size]
                else:
                    d[nums[size]] = size
                size = size +1
solution = Solution()
list = [2,7,11,15]
target = 9
nums = solution.twoSum(list,target)
print(nums)

給列表中的字典排序：假設有以下list對象，alist=[{"name":"a","age":20},{"name":"b","age":30},{"name":"c","age":25}],將alist中的元素按照age從大到小排序 
alist=[{"name":"a","age":20},{"name":"b","age":30},{"name":"c","age":25}]

alist_sort = sorted(alist,key=lambda e: e.__getitem__('age'),reverse=True)

30.python代碼實現刪除一個list裏面的重複元素

def distFunc1(a):
    """使用集合去重"""
    a = list(set(a))
    print(a)

def distFunc2(a):
    """將一個列表的數據取出放到另外一個列表中，中間做判斷"""
    list = []
    for i in a:
        if i not in list:
            list.append(i)
    #若是須要排序的話用sort
    list.sort()
    print(list)

def distFunc3(a):
    """使用字典"""
    b = {}
    b = b.fromkeys(a)
    c = list(b.keys())
    print(c)

if __name__ == "__main__":
    a = [1,2,4,2,4,5,7,10,5,5,7,8,9,0,3]
    distFunc1(a)
    distFunc2(a)
    distFunc3(a)

31.統計一個文本中單詞頻次最高的10個單詞？

import re

# 方法一
def test(filepath):
    
    distone = {}

    with open(filepath) as f:
        for line in f:
            line = re.sub("\W+", " ", line)
            lineone = line.split()
            for keyone in lineone:
                if not distone.get(keyone):
                    distone[keyone] = 1
                else:
                    distone[keyone] += 1
    num_ten = sorted(distone.items(), key=lambda x:x[1], reverse=True)[:10]
    num_ten =[x[0] for x in num_ten]
    return num_ten
    
 
# 方法二 
# 使用 built-in 的 Counter 裏面的 most_common
import re
from collections import Counter


def test2(filepath):
    with open(filepath) as f:
        return list(map(lambda c: c[0], Counter(re.sub("\W+", " ", f.read()).split()).most_common(10)))