标签:eth tput HERE pre without col ring lse you
Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.
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?
M1: 转换成string
time: O(n), space: O(n)
class Solution { public boolean isPalindrome(int x) { String s = Integer.toString(x); int i = 0, j = s.length() - 1; while(i <= j) { if(s.charAt(i) != s.charAt(j)) return false; i++; j--; } return true; } }
M2: 把x反转过来rev,最后如果x=rev,说明是palindrome
time: O(length of x), space: O(1)
class Solution { public boolean isPalindrome(int x) { if(x < 0) return false; int rev = 0; int xx = x; while(xx > 0) { rev = rev * 10 + xx % 10; xx /= 10; } return x == rev; } }
标签:eth tput HERE pre without col ring lse you
原文地址:https://www.cnblogs.com/fatttcat/p/10133225.html