Submission #3179475

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Source Code Expand

use std::cmp::max;
use std::collections::BTreeSet;

macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};

    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };

    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };

    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };

    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };

    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}

fn solve(s: String, k: usize) {
    let mut substrs: BTreeSet<&str> = BTreeSet::new();

    for p in 1..(k+1) {
        for i in 0..(max(s.len() as i32 - p as i32 + 1, 0) as usize) {
            let sub = &s[i..i+p];
            match substrs.iter().nth(k-1).cloned() {
                Some(last) if sub > last => (),
                _ => {
                    substrs.insert(sub);
                },
            }
        }
    }

    println!("{}", substrs.iter().nth(k-1).unwrap());
}

fn main() {
    input!{
        s: String,
        k: usize,
    }

    solve(s,k);
}

Submission Info

Judge Result