算法原链接

https://leetcode-cn.com/problems/palindrome-number/

解法

  1. package main
  3. import (
  4.     "fmt"
  5.     "math"
  6.     "strconv"
  7. )
  9. func main() {
  10.     x := 121
  11.     r := isPalindrome1(x)
  12.     fmt.Println(r)
  13. }
  15. // 字符串解法
  16. func isPalindrome(x int) bool {
  17.     if x < 0 {
  18.         return false
  19.     }
  20.     if x < 10 {
  21.         return true
  22.     }
  24.     s := strconv.Itoa(x)
  26.     l := len(s)
  27.     var left, right int
  29.     if l%2 == 0 {
  30.         left = l/2 - 1
  31.         right = l / 2
  32.     } else {
  33.         middle := float64(l) / float64(2)
  34.         left = int(middle) - 1
  35.         right = int(math.Ceil(middle))
  36.     }
  38.     left, right = test(s, left, right)
  40.     return left == 0 && right == len(s)-1
  41. }
  43. func test(s string, left, right int) (int, int) {
  44.     for ; left >= 0 && right < len(s) && s[left] == s[right]; left, right = left-1, right+1 {
  45.     }
  47.     return left + 1, right - 1
  48. }
  50. // 官方解法
  51. func isPalindrome1(x int) bool {
  52.     if x < 0 || (x != 0 && x%10 == 0) {
  53.         return false
  54.     }
  56.     revertedNumber := 0
  58.     for revertedNumber < x {
  59.         revertedNumber = revertedNumber*10 + x%10
  60.         x /= 10
  61.     }
  63.     return x == revertedNumber || x == revertedNumber/10
  64. }