题目
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?
题目大意
判断一个整数是否是回文数。回文数是指正序（从左向右）和倒序（从右向左）读都是一样的整数。
解题思路
- 判断一个整数是不是回文数。
- 简单题。注意会有负数的情况，负数，个位数，10 都不是回文数。其他的整数再按照回文的规则判断。
代码
package leetcode
import "strconv"
// 解法一
func isPalindrome(x int) bool {
if x < 0 {
return false
}
if x == 0 {
return true
}
if x%10 == 0 {
return false
}
arr := make([]int, 0, 32)
for x > 0 {
arr = append(arr, x%10)
x = x / 10
}
sz := len(arr)
for i, j := 0, sz-1; i <= j; i, j = i+1, j-1 {
if arr[i] != arr[j] {
return false
}
}
return true
}
// 解法二 数字转字符串
func isPalindrome1(x int) bool {
if x < 0 {
return false
}
if x < 10 {
return true
}
s := strconv.Itoa(x)
length := len(s)
for i := 0; i <= length/2; i++ {
if s[i] != s[length-1-i] {
return false
}
}
return true
}