Palindrome Number Problem & Solution
Given an integer x, return true if x is palindrome integer. An integer is a palindrome when it reads the same backward as forward. For example, 121 is palindrome while 123 is not.
See the palindrome number problem on LeetCode.
C++ Solution
#pragma GCC optimize("Ofast")
#pragma GCC optimization("unroll-loops")
static const int _=[](){std::ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();
class Solution {
public:
bool isPalindrome(int x) {
if (x < 0) {
return false;
}
// When reversing a signed int, its reverse can overflow, thus using unsigned int.
uint y = 0;
int tmp = x;
while (tmp != 0) {
y = y * 10 + tmp % 10;
tmp /= 10;
}
while (x != 0) {
if (x % 10 != y % 10) {
return false;
}
x /= 10;
y /= 10;
}
return true;
}
};