思路:变成 Vec 之后进行处理,对不起,我实在是太菜了

use std::io::{self, *};

fn main() {
    let stdin = io::stdin();
    let mut table = vec![0i32,0i32,0i32,0i32,0i32,0i32,0i32,0i32,0i32,0i32];
    for line in stdin.lock().lines() {
        let mut v : Vec<char> = line.unwrap().chars().collect();
        for i in 0..v.len() {
            table[v[i] as usize -48] += 1;
        }
        v.reverse();
        let mut i = v.len() - 1;
        while i > 0 {
            if table[v[i] as usize -48] > 1 {
                table[v[i] as usize -48] -= 1;
                v.remove(i);
            }
            i -= 1;
        }
        let mut s = String::new();
        for i in 0..v.len() {
            s.push(v[i]);
        }
        println!("{}",s);
    }
}