题目:
给出一个 32 位的有符号整数,你需要将这个整数中每位上的数字进行反转。
示例 1:
输入: 123
输出: 321
示例 2:
输入: -123
输出: -321
示例 3:
输入: 120
输出: 21
注意:
假设我们的环境只能存储得下 32 位的有符号整数,则其数值范围为 。请根据这个假设,如果反转后整数溢出那么就返回 0。
解题思路:
1.实现数据的反转
如果是正数:
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tra = 0
while x ! = 0 :
n2 = x % 10
x = x / / 10
tra = tra * 10 + n2
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如果是负数就abs()一下这个数
2.溢出判定
给出范围[−2^31, 2^31 − 1]
则输出的结果tra就必须满足这个范围.
代码:
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class Solution( object ):
def reverse( self , x):
base = 1
for i in range ( 31 ):
base = base * 2
two_Max = base - 1
two_Min = - base
tra = 0
if x < 0 :
x = abs (x)
while x ! = 0 :
n2 = x % 10
if tra > abs (two_Min) / / 10 or (tra = = abs (two_Min) / / 10 and n2 < - 8 ):
return 0
x = x / / 10
tra = tra * 10 + n2
return - tra
else :
while x ! = 0 :
n2 = x % 10
if tra > two_Max / / 10 or (tra = = two_Max and n2 > 7 ):
return 0
x = x / / 10
tra = tra * 10 + n2
return tra
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补充:python实现数字反转_python 数字怎么反转
每次写 Python 都会忘记该怎么写,最后只能去 Stack Overflow 查?我也一样。时间一长,这让人厌倦。
这15个 Python 技巧和窍门,可以帮你提高效率
1. 交换值
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x, y = 1 , 2
print (x, y)
x, y = y, x
print (x, y)
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2. 字符串列表合并为一个字符串
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sentence_list = [ "my" , "name" , "is" , "George" ]
sentence_string = " " .join(sentence_list)
print (sentence_string)
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3. 将字符串拆分为子字符串列表
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sentence_string = "my name is George"
sentence_string.split()
print (sentence_string)
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4. 通过数字填充初始化列表
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[ 0 ] * 1000
# List of 1000
zeros [ 8.2 ] * 1000
# List of 1000 8.2's
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5. 字典合并
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x = { 'a' : 1 , 'b' : 2 }
y = { 'b' : 3 , 'c' : 4 }
z = { * * x, * * y}
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6. 反转字符串
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name = "George" name[:: - 1 ]
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7. 从函数返回多个值
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def get_a_string():
a = "George"
b = "is"
c = "cool" return a, b, c
sentence = get_a_string() (a, b, c) = sentence
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8. 列表解析式
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a = [ 1 , 2 , 3 ]
b = [num * 2 for num in a] # Create a new list by multiplying each element in a by 2
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9. 遍历字典
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m = { 'a' : 1 , 'b' : 2 , 'c' : 3 , 'd' : 4 } for key, value in m.items(): print ( '{0}: {1}' . format (key, value))
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10. 同时遍历列表的索引和值
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m = [ 'a' , 'b' , 'c' , 'd' ] for index, value in enumerate (m): print ( '{0}: {1}' . format (index, value))
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11. 初始化空容器
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a_list = list ()
a_dict = dict ()
a_map = map ()
a_set = set ()
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12. 删除字符串两端的无用字符
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name = " George " name_2 = "George///" name.strip() # prints "George" name_2.strip("/") # prints "George"
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13. 列表中出现最多的元素
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test = [ 1 , 2 , 3 , 4 , 2 , 2 , 3 , 1 , 4 , 4 , 4 ] print ( max ( set (test), key = test.count))
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14. 检查对象的内存使用情况
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import sys x = 1 print (sys.getsizeof(x))
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15. 将 dict 转换为 XML
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from xml.etree.ElementTree import Element def dict_to_xml(tag, d): ''' Turn a simple dict of key/value pairs into XML ''' elem = Element(tag) for key, val in d.items(): child = Element(key) child.text = str(val) elem.append(child) return elem
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以上为个人经验,希望能给大家一个参考,也希望大家多多支持服务器之家。如有错误或未考虑完全的地方,望不吝赐教。
原文链接:https://www.cnblogs.com/justkeep/p/11385721.html