【工程

https://codeforces.com/contest/1431

练习Kotlin的基本操作：输入输出、数组定义与遍历，数组排序，防止溢出

import java.util.*
import kotlin.math.*

fun main() {
    val read = Scanner(System.`in`)
    var t = read.nextInt()
    while (t-- > 0) {
        var n = read.nextInt()
        var a = Array(n) { 0L }
        for (i in a.indices)
            a[i] = read.nextLong()
        a.sortDescending()
        var cnt = 0L
        var ans = 0L
        for (ai in a) {
            ++cnt
            var tmp = cnt * ai
            ans = max(ans, tmp)
        }
        println(ans)
    }
}

暂时不知道怎么用foreach修改里面的元素
有一说一kt是真的简洁，不用c++那样传一堆东西。
也可以直接sortDescending()。

import java.util.*
import kotlin.math.*

fun main() {
    val read = Scanner(System.`in`)
    var t = read.nextInt()
    while (t-- > 0) {
        var str = read.next()
        var n = str.length
        var dp = Array(2) { Array(n + 1) { 0 } }
        for (i in 1..n) {
            dp[1][i] = dp[0][i - 1]
            if (str[i - 1] == 'w') {
                dp[0][i] = min(dp[0][i - 1], dp[1][i - 1]) + 1
                dp[1][i] = Int.MAX_VALUE / 2
            } else if (str[i - 1] == 'v') {
                dp[0][i] = dp[1][i - 1] + 1
                dp[1][i] = dp[0][i - 1]
            }
        }
        println(min(dp[0][n], dp[1][n]))
    }
}

import java.util.*
import kotlin.math.*

fun main() {
    val read = Scanner(System.`in`)
    var t = read.nextInt()
    while (t-- > 0) {
        var n = read.nextInt()
        var k = read.nextInt()
        var p = Array(n + 2) { 0 }
        for (i in 1..n)
            p[i] = read.nextInt()
        p.reverse()
        var ans = 0L
        for (x in 1..n) {
            var tmp = 0L
            var cnt = x - x / k
            for (i in cnt + 1..x)
                tmp += p[i]
            ans = max(ans, tmp)
        }
        println(ans)
    }
}