回文數字,即77、242、3993、12321之類的數字稱之為回文數字
題目的難點在于不允許使用額外的空間,隻能将數字的首位挨個比較。
java代碼如下
public class Solution {
public boolean isPalindrome(int x) {
if(x < )
{
return false;
}
else
{
int len = , num = x;
int leftIndex = , rightIndex = , left, right;
while(num > )
{
num = num / ;
len++;
if(leftIndex == )
{
leftIndex = ;
}
else
{
leftIndex *= ;
}
}
num = x;
for(int i = ; i < len / ; i++)
{
left = (num / leftIndex) % ;
right = (num / rightIndex) % ;
leftIndex /= ;
rightIndex *= ;
if(left != right)
{
return false;
}
}
return true;
}
}
}