Robotti

warning: variable does not need to be mutable
  --> input/code.rs:48:13
   |
48 |         let mut new_pos: u32;
   |             ----^^^^^^^
   |             |
   |             help: remove this `mut`
   |
   = note: `#[warn(unused_mut)]` on by default

warning: 1 warning emitted

use std::io;

fn main() {
    let stdin = io::stdin();

    let n: u32 = {
        let mut input: String = String::new();
        stdin.read_line(&mut input).unwrap();
        input.trim().parse().unwrap()
    };

    let mut robot_pos = n;
    let mut left_rooms = Vec::new();
    let mut right_rooms = Vec::new();

    {
        let mut input: String = String::new();
        stdin.read_line(&mut input).unwrap();
        let mut chars = input.chars();

        for i in 0..n {
            match chars.next() {
                Some('.') => {},
                Some('*') => {
                    if i < robot_pos {
                        left_rooms.push(i);
                    } else {
                        right_rooms.push(i);
                    }
                },
                Some('R') => {
                    robot_pos = i;
                },
                None => panic!("too short input"),
                _ => panic!("illegal char"),
            }
        }

        right_rooms.reverse(); // Closest rooms go last.
    };

    let mut steps: u32 = 0;
    let mut coins: u32 = 0;
    loop {
        let left_distance = left_rooms.last().map_or(u32::MAX, |x| robot_pos - x); // x < robot_pos
        let right_distance = right_rooms.last().map_or(u32::MAX, |x| x - robot_pos); // x > robot_pos

        let mut new_pos: u32;
        if left_distance < right_distance {
            new_pos = left_rooms.pop().unwrap();
        } else if right_distance < left_distance {
            new_pos = right_rooms.pop().unwrap();
        } else {
            break;
        }

        coins += 1;
        steps += robot_pos.abs_diff(new_pos);
        robot_pos = new_pos;
    }

    println!("{} {}", steps, coins);
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 1, 2

Verdict: ACCEPTED

Test 3

Group: 1, 2

Verdict: ACCEPTED

Test 4

Group: 1, 2

Verdict: ACCEPTED

Test 5

Group: 1, 2

Verdict: ACCEPTED

Test 6

Group: 1, 2

Verdict: ACCEPTED

Test 7

Group: 1, 2

Verdict: ACCEPTED

Test 8

Group: 1, 2

Verdict: ACCEPTED

Test 9

Group: 1, 2

Verdict: ACCEPTED

Test 10

Group: 1, 2

Verdict: ACCEPTED

Test 11

Group: 1, 2

Verdict: ACCEPTED

Test 12

Group: 2

Verdict: ACCEPTED

Test 13

Group: 2

Verdict: ACCEPTED

Test 14

Group: 2

Verdict: ACCEPTED

Test 15

Group: 2

Verdict: ACCEPTED

Test 16

Group: 2

Verdict: ACCEPTED

Test 17

Group: 2

Verdict: ACCEPTED

Test 18

Group: 2

Verdict: ACCEPTED

Test 19

Group: 2

Verdict: ACCEPTED

Test 20

Group: 2

Verdict: ACCEPTED

Test 21

Group: 2

Verdict: ACCEPTED

Test 22

Group: 2

Verdict: ACCEPTED

Test 23

Group: 2

Verdict: ACCEPTED

Test 24

Group: 2

Verdict: ACCEPTED