3SUM

warning: unused imports: `Reverse`, `max`, `min`
 --> input/code.rs:1:16
  |
1 | use std::cmp::{max, min, Reverse};
  |                ^^^  ^^^  ^^^^^^^
  |
  = note: `#[warn(unused_imports)]` on by default

warning: unused imports: `BTreeMap`, `BinaryHeap`, `HashSet`
 --> input/code.rs:2:24
  |
2 | use std::collections::{BTreeMap, BinaryHeap, HashMap, HashSet};
  |                        ^^^^^^^^  ^^^^^^^^^^           ^^^^^^^

warning: unused import: `std::process::exit`
 --> input/code.rs:4:5
  |
4 | use std::process::exit;
  |     ^^^^^^^^^^^^^^^^^^

warning: 3 warnings emitted

use std::cmp::{max, min, Reverse};
use std::collections::{BTreeMap, BinaryHeap, HashMap, HashSet};
use std::io::{self, Read};
use std::process::exit;

macro_rules! input {
    ($it: expr) => {
        $it.next().unwrap().parse().unwrap()
    };
    ($it: expr, $T: ty) => {
        $it.next().unwrap().parse::<$T>().unwrap()
    };
}
/*
mod classes;
mod homework;

fn main() {
    // println!("{}", "-".repeat(20));
    // classes::c13::task2();
    homework::hw5::task2();
    // println!("{}", "-".repeat(20));
}
// */

use std::hash::{Hasher, BuildHasher};

struct IdentityHasher(usize);

impl Hasher for IdentityHasher {
    fn finish(&self) -> u64 {
        self.0 as u64
    }

    fn write(&mut self, _: &[u8]) {}

    fn write_usize(&mut self, i: usize) {
        self.0 = i;
    }
}

struct IdentityHasherBuilder;

impl BuildHasher for IdentityHasherBuilder {
    type Hasher = IdentityHasher;

    fn build_hasher(&self) -> Self::Hasher {
        IdentityHasher(0)
    }
}



fn main() {
    let mut buf = String::new();
    io::stdin().read_to_string(&mut buf).unwrap();

    let mut it = buf.split_whitespace();

    let (n, x): (usize, usize) = (input!(it), input!(it));

    let v: Vec<usize> = (0..n).map(|_| input!(it)).collect();

    let mut m: HashMap<usize, Vec<(usize, usize)>> = HashMap::new();

    for i in 0..n {
        for j in i + 1..n {
            let sum = v[i] + v[j];
            if sum < x {
                let target = x - sum;
                if let Some(l) = m.get(&target) {
                    for &(a, b) in l {
                        if a != i && a != j && b != i && b != j {
                            println!("{} {} {} {}", a + 1, b + 1, i + 1, j + 1);
                            return;
                        }
                    }
                }
                m.entry(sum).or_insert_with(Vec::new).push((i, j));
            }
        }
    }

    println!("IMPOSSIBLE");
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: ACCEPTED

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: WRONG ANSWER

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: WRONG ANSWER

Test 10

Verdict: WRONG ANSWER

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: WRONG ANSWER

Test 17

Verdict: WRONG ANSWER

Test 18

Verdict: WRONG ANSWER

Test 19

Verdict: ACCEPTED

Test 20

Verdict: WRONG ANSWER

Test 21

Verdict: WRONG ANSWER

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED