Constructing a Number - HackerRank Problems: https://www.hackerrank.com/challenges/constructing-a-number

constructing-a-number-English.pdf

input.txt

100
1
1
1
2
1
3
1
4
1
5
1
6
1
7
1
8
1
9
1
10
1
11
1
12
1
13
1
14
1
15
1
16
1
17
1
18
1
19
1
20
1
1000000
1
999999
1
999998
1
999997
1
999996
1
999995
1
999994
1
999993
1
999992
1
999991
1
999990
1
999989
1
999988
1
999987
1
999986
1
999985
1
999984
1
999983
1
999982
1
999981
1
101010
1
260522
1
914575
1
436426
1
979445
1
648772
1
690081
1
933447
1
190629
1
703497
1
47202
1
407775
1
894325
1
963982
1
804784
1
968417
1
302156
1
631932
1
735902
1
895728
1
78537
1
723857
1
330739
1
286918
1
329211
1
539679
1
238506
1
63340
1
686568
1
361868
1
660016
1
287940
1
296263
1
224593
1
601449
1
836991
1
890310
1
823355
1
177068
1
11431
1
8580
1
291757
1
449218
1
374934
1
594328
1
163676
1
829355
1
996221
1
899080
1
195922
1
531545
1
748511
1
34067
1
575467
1
338674
1
284691
1
206504
1
999835
1
262034
1
344965

main.rs

#![feature(iterator_step_by)]
use std::io::{self, Read};
/**
 * Divisibility by 3 or 9.
 * - First, take any number (for this example it will be 492)
 * and add together each digit in the number (4 + 9 + 2 = 15).
 * Then take that sum (15) and determine if it is divisible by 3.
 * - The original number is divisible by 3 (or 9)
 * if and only if the sum of its digits is divisible by 3 (or 9).
*/
fn can_construct(nums: &mut [u32]) -> &'static str {
    let sum: u32 = nums.iter().sum();
    if sum % 3 == 0 {
        "Yes"
    } else {
        "No"
    }
}

fn main() {
    let mut line = Vec::new();
    let stdin = io::stdin();
    stdin
        .lock()
        .read_to_end(&mut line)
        .expect("Could not read line");
    let buf = String::from_utf8(line).expect("Error While Convert STDIN to String");
    for l in buf.lines().skip(2).step_by(2) {
        let str_nums: Vec<&str> = l.split_whitespace().collect();
        let mut nums: Vec<u32> = str_nums
            .into_iter()
            .map(|num| num.parse().expect("Error While Converting To u32"))
            .collect();
        println!("{}", can_construct(&mut nums));
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn test_can_construct() {
        assert_eq!(can_construct(&mut [1, 3, 5]), "Yes"); // 135
        assert_eq!(can_construct(&mut [2, 3, 5, 2]), "Yes"); // 2352
        assert_eq!(can_construct(&mut [90, 40, 50]), "Yes"); // 904050
        assert_eq!(can_construct(&mut [1999, 2000, 2001, 2003]), "No"); // 1999200020012003
    }
}

output.txt

No
No
Yes
No
No
Yes
No
No
Yes
No
No
Yes
No
No
Yes
No
No
Yes
No
No
No
Yes
No
No
Yes
No
No
Yes
No
No
Yes
No
No
Yes
No
No
Yes
No
No
Yes
Yes
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
Yes
No
Yes
Yes
No
No
No
Yes
Yes
Yes
No
Yes
No
No
Yes
No
No
Yes
Yes
Yes
No
No
No
Yes
No
No
Yes
No
No
No
No
No
No
No
No
No
No
No
Yes
No
No
No
No