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使用python实现回文数的四种方法小结

更新时间:2020-08-09 21:36:01 作者:startmvc
回文数就是指整数倒过来和原整数相等。Example1:Input:121Output:trueExample2:Input:-121Output:falseExplan

回文数就是指整数倒过来和原整数相等。


Example 1:
 
Input: 121
Output: true

Example 2:
 
Input: -121
Output: false
Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.

Example 3:
 
Input: 10
Output: false
Explanation: Reads 01 from right to left. Therefore it is not a palindrome.

1:整数转字符串,通过下标对比确定该整数是否为回文数


str_x = str(x)
for i in range(0,int(len(str_x)/2)):
 if str_x[i] != str_x[-i-1]:
 return False
return True

2:字符串切片操作,str[index:index:step],中括号里面分别为:字符起点、终点和步长


str_x = str(x)
return str_x == str_x[::-1]

3:数学计算的方法,对比反转整数的值


if x<0:
 return False
temp_x = x;
palindromeNum = 0
while temp_x != 0:
 palindromeNum = palindromeNum*10 + temp_x%10
 temp_x /= 10
return palindromeNum == x

4:整数转字符串,反转字符串,对比反转后字符串与原字符串是否相等


str_x = str(x)
str_y = ""
for i in str_x:
 str_y = i + str_y
return str_y == str_x

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python 回文数