Problem:
Score : 300 points

Problem Statement

You are given two non-negative integers L and R.
We will choose two integers i and j such that L \leq i < j \leq R.
Find the minimum possible value of (i \times j) \mbox{ mod } 2019.

Constraints

All values in input are integers.

0 \leq L < R \leq 2 \times 10^9

Input

Input is given from Standard Input in the following format:

L R

Output

Print the minimum possible value of (i \times j) \mbox{ mod } 2019 when i and j are chosen under the given condition.

Sample Input 1

2020 2040

Sample Output 1

2

When (i, j) = (2020, 2021), (i \times j) \mbox{ mod } 2019 = 2.

Sample Input 2

4 5

Sample Output 2

20

We have only one choice: (i, j) = (4, 5).

Solution in Kotlin (1.0.0) (judge verdict: Accepted)


import java.io.PrintWriter

val squares = (1..127).map { it * it }

fun check(x: List<Int>, y: List<Int>): Boolean {
    val distanceSquared = x.zip(y).map { (it.first - it.second) * (it.first - it.second)}.sum()
    return distanceSquared in squares
}

fun solve(out: PrintWriter): Boolean = with(out) {
    val (L, R) = readLine()!!.split(" ").map { it.toInt() }

    val Lmod2019 = if ((L/2019+1) * 2019 <= R) 0 else L % 2019
    val Rmod2019 = if ((R/2019) * 2019 >= L) 2018 else R % 2019

    var m = Int.MAX_VALUE
    for (i in Lmod2019..Rmod2019) {
        for (j in i+1..Rmod2019) {
            if (m > i*j%2019)
                m = i*j%2019
        }
    }
    println(m)
    return false
}

// with(PrintWriter(System.out))
// with(File("out.txt").printWriter())
// with(File(args[1]).printWriter())
fun main(args: Array<String>) = with(PrintWriter(System.out)){
//    System.setIn(File(args[0]).inputStream())
    while(solve(this));
    flush()
}