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96 lines
1.6 KiB
Markdown
96 lines
1.6 KiB
Markdown
# [9. Palindrome Number](https://leetcode.com/problems/palindrome-number/)
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## 题目
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Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.
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**Example 1**:
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```
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Input: 121
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Output: true
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```
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**Example 2**:
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```
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Input: -121
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Output: false
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Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.
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```
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**Example 3**:
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```
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Input: 10
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Output: false
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Explanation: Reads 01 from right to left. Therefore it is not a palindrome.
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```
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**Follow up**:
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Coud you solve it without converting the integer to a string?
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## 题目大意
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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。
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## 解题思路
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- 判断一个整数是不是回文数。
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- 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。
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## 代码
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```go
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package leetcode
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import "strconv"
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// 解法一
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func isPalindrome(x int) bool {
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if x < 0 {
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return false
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}
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if x == 0 {
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return true
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}
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if x%10 == 0 {
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return false
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}
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arr := make([]int, 0, 32)
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for x > 0 {
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arr = append(arr, x%10)
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x = x / 10
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}
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sz := len(arr)
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for i, j := 0, sz-1; i <= j; i, j = i+1, j-1 {
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if arr[i] != arr[j] {
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return false
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}
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}
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return true
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}
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// 解法二 数字转字符串
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func isPalindrome1(x int) bool {
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if x < 0 {
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return false
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}
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if x < 10 {
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return true
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}
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s := strconv.Itoa(x)
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length := len(s)
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for i := 0; i <= length/2; i++ {
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if s[i] != s[length-1-i] {
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return false
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}
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}
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return true
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}
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``` |