|
1 | | -/** |
2 | | - * [9] Palindrome Number |
3 | | - * |
| 1 | +/** |
| 2 | + * [9] Palindrome Number |
| 3 | + * |
4 | 4 | * Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward. |
5 | 5 | * |
6 | 6 | * Example 1: |
|
29 | 29 | * Follow up: |
30 | 30 | * |
31 | 31 | * Coud you solve it without converting the integer to a string? |
32 | | - * |
33 | | - */ |
34 | | -pub struct Solution {} |
35 | | - |
36 | | -// submission codes start here |
37 | | - |
38 | | -impl Solution { |
39 | | - pub fn is_palindrome(x: i32) -> bool { |
40 | | - |
41 | | - } |
42 | | -} |
43 | | - |
44 | | -// submission codes end |
45 | | - |
46 | | -#[cfg(test)] |
47 | | -mod tests { |
48 | | - use super::*; |
49 | | - |
50 | | - #[test] |
51 | | - fn test_9() { |
52 | | - } |
53 | | -} |
| 32 | + * |
| 33 | + */ |
| 34 | +pub struct Solution {} |
| 35 | + |
| 36 | +// submission codes start here |
| 37 | + |
| 38 | +// not optimal, we only have to revert half of the string |
| 39 | +impl Solution { |
| 40 | + pub fn is_palindrome(x: i32) -> bool { |
| 41 | + if x < 0 { return false } |
| 42 | + let mut digits: Vec<i32> = Vec::new(); |
| 43 | + let mut input = x; |
| 44 | + while input != 0 { |
| 45 | + digits.push(input % 10); |
| 46 | + input = input / 10; |
| 47 | + } |
| 48 | + let len = digits.len(); |
| 49 | + // handle one digit |
| 50 | + if len < 2 { return true } |
| 51 | + // handle end with 0 |
| 52 | + if digits[0] == 0 { return false } |
| 53 | + let mut i = 0; |
| 54 | + while i < len / 2 { |
| 55 | + if digits[i] != digits[len - 1 - i] { |
| 56 | + return false |
| 57 | + } |
| 58 | + i += 1; |
| 59 | + } |
| 60 | + true |
| 61 | + } |
| 62 | +} |
| 63 | + |
| 64 | +// submission codes end |
| 65 | + |
| 66 | +#[cfg(test)] |
| 67 | +mod tests { |
| 68 | + use super::*; |
| 69 | + |
| 70 | + #[test] |
| 71 | + fn test_9() { |
| 72 | + assert_eq!(Solution::is_palindrome(-32), false); |
| 73 | + assert_eq!(Solution::is_palindrome(10), false); |
| 74 | + assert_eq!(Solution::is_palindrome(0), true); |
| 75 | + assert_eq!(Solution::is_palindrome(9), true); |
| 76 | + assert_eq!(Solution::is_palindrome(121), true); |
| 77 | + assert_eq!(Solution::is_palindrome(2222), true); |
| 78 | + assert_eq!(Solution::is_palindrome(11222211), true); |
| 79 | + } |
| 80 | +} |
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