题目
Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.
确定整数是不是回文数,当整数向前和向后读相同的时候,就是回文数
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.
说明:从左向右为-121,从右向左为121-,所以它不是回文数
Example 3:
Input: 10
Output: false
Explanation: Reads 01 from right to left. Therefore it is not a palindrome.
说明:从右向左读为01,因此它不是回文数
Follow up:
Coud you solve it without converting the integer to a string?
你能不能将整数换为字符串?
代码
class Solution {
public boolean isPalindrome(int x) {
if(x<0)
{
return false;
}
if(x==0)
{
return true;
}
StringBuilder in = new StringBuilder();
int a = x;
while(a!=0)
{
in.append(a%10);
a/=10;
}
String o = String.valueOf(x);
if(o.equals(in.toString()))
{
return true;
}else
{
return false;
}
}
}
注意不要使用StringBuffer,StringBuffer在单线程下效率并不高。
StringBuffer为287ms
StringBuilder为99ms
可以看出StringBuffer在单线程下的重复加锁解锁操作耗费了大量时间