Python经典面试题与参考答案集锦
一些面试题
1.列表的遍历问题(0507)
list_1 = [10, 20, 30, 40, 50] # 不能对一个列表同时进行 遍历 和 增删元素 for element in list_1: print(element) if element == 30 or element == 40: list_1.remove(element) print(list_1)
# 改进 temp_list = list() # 先遍历列表,记录下需要增删的元素 for element in list_1: print(element) if element == 30 or element == 40: temp_list.append(element) # 遍历完列表,再对需要增删的内容进行逐一处理 for element in temp_list: list_1.remove(element) print(list_1)
2.字典排序 (0530)
# 题目1 # 按照score的值进行排序。 list_a = [ {"name": "p1", "score": 100}, {"name": "p2", "score": 10}, {"name": "p3", "score": 30}, {"name": "p4", "score": 40}, {"name": "p5", "score": 60}, ] print(sorted(list_a, key=lambda a: a["score"], reverse=False))
# 题目2 # 一行代码 通过filter 和 lambda 函数输出以下列表索引为奇数的对应的元素 list_b = [12, 232, 22, 2, 2, 3, 22, 22, 32]
方法一:
new_list=[x[1] for x in fliter(lambdy x:x[0]%2==1,enumerate(list_b))]
方法二:
for index, element in enumerate(list_b): print("") if index % 2 == 0 else print(element)
3.给定三个整数 a, b, c 求和 ,求和之前需要删除里面相同的整数
示例:
loneSum(1, 2, 3) -> 6
loneSum(3, 2, 3) -> 2
loneSum(3, 3, 3) -> 0
loneSum1 = (1, 2, 3) loneSum2 = (3, 2, 3) loneSum3 = (3, 3, 3) counter = int() for element in loneSum1: if loneSum1.count(element) == 1: counter += element print(counter)
4.给出一个字符串,找出头尾的镜像字符串,即从头正序,从尾倒叙相同的字符串;
示例:
mirrorEnds("abXYZba") -> "ab"
mirrorEnds("abca") -> "a"
mirrorEnds("aba") -> "aba"
def main(source_str): reverse_str = source_str[::-1] for i in range(len(source_str)): if reverse_str[:(i+1)] != source_str[:(i+1)]: return source_str[:i] if reverse_str == source_str: return source_str if __name__ == '__main__': print(main(mirrorEnds))
5.给定一个整数系列 N1, N2…;以及整数M, M是整数系列中的最大数; 从整数系列中取三个数, 可以重复取,要求三个数的和为M。 求所有的可能结果, 并剔除具有相同的结果,得到排序不同的结果。
示例:数列N: [1, 3, 5, 7, 9, 11, 13, 15], 和 M 为17, 返回结果是
[1, 1, 15], [1, 3, 13], [1, 5, 11], [1, 7, 9], [3, 3, 11], [3, 5, 9], [3, 7, 7], [5, 5, 7]
num_list = [1, 3, 5, 7, 9, 11, 13, 15] M = 17 for i in range(len(num_list)): for j in range(i, len(num_list)): for k in range(j, len(num_list)): if num_list[i] + num_list[j] + num_list[k] == M: print((num_list[i], num_list[j], num_list[k]))
6.MRO继承的问题
求三次输出的 Parent.x, Child1.x, Child2.x 分别是多少?
lass Parent(object): x = 1 class Child1(Parent): pass class Child2(Parent): pass print(Parent.x, Child1.x, Child2.x) Child1.x = 2 print(Parent.x, Child1.x, Child2.x) Parent.x = 3 print(Parent.x, Child1.x, Child2.x) # 提示:print(Child1.__mro__) #答案:1,1,1 1,2,1 3,2,3
7.参数传递的问题
第一题
class Counter(): def __init__(self, count=0): self.count = count def main(): c = Counter() c.name = "zhangsan" times = 0 for i in range(10): increment(c, times) print("count is {0}".format(c.count)) print("times is {0}".format(times)) def increment(c, times): times += 1 c.count += 1 if __name__ == "__main__": main() #答案: # count is 10 # times is 0
第二题
class Count(object): def __init__(self, count=0): self.count = count def main(): c = Count() n = 1 m(c, n) print("count is {0}".format(c.count)) print("n is {0}".format(n)) def m(c, n): c = Count(5) n = 3 if __name__ == '__main__': main() #答案: # count is 0 # n is 1
8.装饰器/闭包面试题(0615)
def outFun(a): def inFun(x): return a * x return inFun flist1 = [outFun(a) for a in range(3)] for func in flist1: print(func(1)) # fist2 = [lambda x:a*x for a in range(3)] flist2 = [lambda x:a*x for a in range(4)] for func in flist2: print(func(2)) # 答案: 0 1 2, 6 6 6 6
9.字典排序题(zrc)
s = [{1: "a"}, {3: "c"}, {2: "b"}]
请按照字母acsii码排序
print(sorted(s, key = lambda x: tuple(x.values())[0]))
或
print(sorted(s, key = lambda x: list(x.values())[0]))
sorted 语法:
sorted(iterable[, cmp[, key[, reverse]]])
参数说明:
- iterable -- 可迭代对象。
- cmp -- 比较的函数,这个具有两个参数,参数的值都是从可迭代对象中取出,此函数必须遵守的规则为,大于则返回1,小于则返回-1,等于则返回0。
- key -- 主要是用来进行比较的元素,只有一个参数,具体的函数的参数就是取自于可迭代对象中,指定可迭代对象中的一个元素来进行排序。
- reverse -- 排序规则,reverse = True 降序 , reverse = False 升序(默认)。
返回重新排序的列表。
10.冒泡排序题(zrc)
def sor(): li=[{1:"b"},{3:"c"},{2:"a"}] for i in range(len(li)): for j in range(len(li) - i - 1): v1 = [value for value in list(li[j].values())][0] v2 = [value for value in list(li[j+1].values())][0] print(v1,v2) if v1 > v2: li[j],li[j+1] = li[j+1],li[j] return li ret = sor() print(ret)
11.二分法查找(zrc)
def bin_search(data_set, value): low = 0; high = len(data_set) - 1 while True: mid = (low + high) // 2 if data_set[mid] > value: high = mid - 1 elif data_set[mid] < value: low = mid + 1 else: a = b = mid while data_set[a] == value and a >= 0: a -= 1 while data_set[b] == value and b < len(data_set) - 1: b += 1 return (a+1, b) ret = bin_search([8,8,8,8], 8) print(ret)
12.a=[1,2,3,4,5,6],打印出所有以偶数为key,奇数为值的字典
print({key: value for key, value in zip([i for i in a if i % 2 == 0], [i for i in a if i % 2 != 0])})
13.写一个函数实现阶乘
def factorial(num): counter = 1 for i in range(1, num+1): counter *= i return counter print(factorial(5))
14.有字符串a=‘hsfbsadgasdgvnhhhadhaskdhwqhcjasd’,求出现次数最多的前四个
第一种解法:
def search(a): # 省略校验逻辑 # 生成包含 element 和 count 数据的集合 data_set = {(element, count) for element, count in zip(a, [a.count(i) for i in a])} print(data_set) # 转换成列表类型,进行倒序排序 data_list = list(data_set) new_data_list = sorted(data_list, key=lambda x: x[1], reverse=True) # 取出前四名 new_data_list = new_data_list[0:4] # 拼接字符串 return "".join([i[0] for i in new_data_list]) print(search(a))
第二种简单解法:
a = 'hsfbsadgasdgvnhhhadhaskdhwqhcjasd' # 导入Counter模块 from collections import Counter # 创建对象 count = Counter(a) # 获取出现频率最高的四个字符 print(count.most_common(4)) # 输出:[('h', 7), ('s', 5), ('a', 5), ('d', 5)]
15.sorted排序
if other_allocated_amount: data_list.append({ "shop_id": 0, "shop_name": "其他", "destination": 2, "current_storage": 0, "demand_amount": 0, "allocated_amount": other_allocated_amount, "priority": 0, "negative_order": 0 }) # 按优先级排序 data_list = sorted(data_list, key=lambda d: d["priority"], reverse=True) shop_order = {"仓库": -999, "总部": 1, "刘园": 2, "侯台": 3, "咸水沽": 4, "华明": 5, "大港": 6, "杨村": 7, "新立": 8, "大寺": 9, "汉沽": 10, "沧州": 11, "静海": 13, "芦台": 14, "工农村": 15, "唐山": 16, "廊坊": 17, "哈尔滨": 18, "西青道": 19, "双鸭山": 20, "承德": 21, "张胖子": 22, "固安": 23, "燕郊": 24, "胜芳": 25, "蓟县": 26, } data_list = sorted(data_list, key=lambda d: shop_order.get(d["shop_name"], 999))
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