sum

import java.time.LocalTime
import kotlin.random.Random

fun main() {
    println("Array's size:")
    val m = readLine()!!.trim().toInt()

    println("Threads amount")
    val n = readLine()!!.trim().toInt()

    val arr = IntArray(m) { Random.nextInt(1000) }

    /*println("Array: ")
    arr.forEach { print("$it ") }.apply(::println)*/

    // --------------------------------------- SINGLE ---------------------------------------

    val res1 = {
        val start = LocalTime.now().nano
        val res = arr.sum()
        val finish = LocalTime.now().nano
        println("Single thread: ${maxOf(start, finish) - minOf(start, finish)}")
        res
    }()

    // --------------------------------------- MULTI ---------------------------------------

    val res2 = {
        val start = LocalTime.now().nano
        val _d = m / n
        val numsInThreads = IntArray(n) { _d }
        val ost = m % n
        (0 until ost).forEach { numsInThreads[it]++ }

        var cur = 0
        var res = 0
        val threads = Array(n) { Thread() }
        val _a = Any()

        numsInThreads.forEachIndexed { ind, numsAmount ->
            val _cur = cur

            threads[ind] = Thread {
                var subRes = 0
                val f = _cur + numsAmount
                (_cur until f).forEach { subRes += arr[it] }
                synchronized(_a) { res += subRes }
            }.apply(Thread::start)

            cur += numsAmount
        }

        threads.forEach(Thread::join)

        val finish = LocalTime.now().nano
        println("Multi thread:  ${maxOf(start, finish) - minOf(start, finish)}")
        res
    }()

    if (res1 != res2) throw Exception("Sums are not equal")
}