Palindrome Rearranging

Rust Palindrome Rearranging

use std::collections::HashMap;

fn palindrome_rearranging(input_string: &str) -> bool {
    let mut counts: HashMap<char, i64> = HashMap::new();
    for c in input_string.chars() {
        *counts.entry(c).or_insert(0) += 1;
    }

    counts.values().filter(|&&v| v % 2 != 0).count() <= 1
}

This counts character frequency and checks whether the string has the right number of odd counts to form a palindrome.