题解 | #删除字符串中出现次数最少的字符#

记得把无关的空格 trim 掉

use std::io;
use std::collections::HashMap;

fn main() {
    let mut s = String::new();
    let mut map:HashMap<u8,u8> = HashMap::new();
    io::stdin()
        .read_line(&mut s)
        .expect("Failed to read line");
    let mut v = Vec::from(s.trim());
    for i in v.iter() {
        let num = match map.get(i){
            Some(val) => *val + 1,
            None => 1u8,
        };
        map.insert(*i, num);
    }
    let (&_a,&b) = map.iter().min_by_key(|(_x,y)| **y ).unwrap();
    for i in map {
        if i.1 == b {
            for j in (0..v.len()).rev() {
                if v[j] == i.0 {
                    v.remove(j);
                }
            }
        }
    }
    for i in v {
        print!("{}",char::from(i));
    }
}