Järjestys

use std::io::BufRead;

const MOD: usize = 1_000_000_007;

fn solve(a: Vec<usize>, x: usize) -> usize {
    let a = {
        let mut a = a;
        a.sort();
        a
    };
    let mut res = 1;
    for (i, v) in a.iter().enumerate() {
        // How many values are at most x smaller
        let k = (0..i)
            .rev()
            .map(|j| a[j])
            .take_while(|c| v - c <= x)
            .count();
        res *= k + 1;
        res %= MOD;
    }
    res
}

fn main() {
    let stdin = std::io::stdin();
    let stdin = stdin.lock();
    let mut lines = stdin.lines();

    let t: usize = lines.next().unwrap().unwrap().parse().unwrap();
    for _ in 0..t {
        let nx: Vec<usize> = lines
            .next()
            .unwrap()
            .unwrap()
            .split_whitespace()
            .map(|v| v.parse().unwrap())
            .collect();
        let (_n, x) = (nx[0], nx[1]);
        let input: Vec<usize> = lines
            .next()
            .unwrap()
            .unwrap()
            .split_whitespace()
            .map(|v| v.parse().unwrap())
            .collect();
        println!("{}", solve(input, x));
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_sample() {
        assert_eq!(solve(vec![1], 5), 1);
        assert_eq!(solve(vec![1, 2, 3], 1), 4);
        assert_eq!(solve(vec![2, 100, 95, 999, 1, 77, 6, 8], 42), 144);
    }
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 2

Verdict: ACCEPTED

Test 3

Group: 2

Verdict: ACCEPTED