【LeetCode】126.Palindrome Number
阿新 • • 發佈:2018-11-13
題目描述(Easy)
Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.
題目連結
https://leetcode.com/problems/palindrome-number/description/
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.
Follow up:
Coud you solve it without converting the integer to a string?
演算法分析
不斷取當前第一位和最後一位進行比較,往中間收縮,直到找到不一樣的位。
提交程式碼:
class Solution { public: bool isPalindrome(int x) { if (x < 0) return false; int decades = 1; while(x / decades >= 10) decades *= 10; while(x > 0) { int beg = x / decades; int end = x % 10; if (beg != end) return false; x = x % decades / 10; decades /= 100; } return true; } };