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Detect whether an (extended) ASCII string is a palindrome anagram using Rust
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// Given a string, how do you determine whether it's an anagram of a palindrome? | |
// Solution: Given the unique set of chars, at most 1 should appear in the string | |
// an odd number of times. | |
// chars() returns Unicode Scalar Values, and these might not match up | |
// with grapheme clusters, so this can't be assumed to work correctly | |
// for anything other than (extended) ASCII | |
fn unique_chars(s: &str) -> String { | |
let mut v: Vec<char> = s.chars().collect(); | |
// dedup removes consecutive identical elements, so we need a sort first | |
v.sort_unstable(); | |
v.dedup(); | |
v.into_iter().collect() | |
} | |
/// Count the number of odd occurrences of each unique char in the string | |
/// If the sum is greater than 1, no palindrome is possible | |
fn possible_palindrome(letters: &str) -> bool { | |
let uniq = unique_chars(letters); | |
uniq.chars() | |
.map(|char| letters.matches(char).count() % 2) | |
.sum::<usize>() | |
<= 1 | |
} | |
fn main() { | |
let pal = "ABBBBAF"; | |
let npal = "DABBAF"; | |
assert_eq!(possible_palindrome(pal), true); | |
assert_eq!(possible_palindrome(npal), false); | |
} |
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