Quick Test CLI provides full support for Kotlin with automatic compilation and execution of your competitive programming solutions.
File Extension
Kotlin files must use the .kt extension:
main.kt
correct.kt
gen.kt
Compilation
Kotlin files are compiled using kotlinc with the following command:
kotlinc main.kt -include-runtime -d .qt/main.jar
Compilation Options
-include-runtime - Includes the Kotlin runtime library in the JAR file-d .qt/main.jar - Specifies the output JAR file location
The compiled output is a JAR file that includes the Kotlin runtime, making it standalone and executable.
Execution
After compilation, the JAR is executed with:
Example Code
Here’s a typical Kotlin solution for competitive programming:
fun main() {
// Maximum Subarray Problem
val n = readLine()!!.toInt()
val a = readLine()!!.split(" ").map { it.toInt() }
var best = 0
for (i in 0..n-1) {
var sum = 0
for (j in i..n-1) {
sum += a[j]
best = best.coerceAtLeast(sum)
}
}
println(best)
}
Usage with Quick Test
Compare Mode (cmp)
Compare your solution against a brute-force correct solution:
quicktest cmp --target-file=main.kt --correct-file=correct.kt --gen-file=gen.kt
Stress Testing Mode
Test your solution’s performance:
quicktest stress --target-file=main.kt --gen-file=gen.kt --tout 2000 --tc 1000
Checker Mode
For problems with multiple valid answers:
quicktest check --target-file=main.kt --checker-file=checker.kt --gen-file=gen.kt
Requirements
You must have the Kotlin compiler (kotlinc) and Java Runtime Environment (JRE) installed on your system.
kotlinc -version
java -version
Installing Kotlin
Kotlin can be installed via:
- SDKMAN:
sdk install kotlin
- Homebrew (macOS):
brew install kotlin
- Manual: Download from kotlinlang.org
// Single integer
val n = readLine()!!.toInt()
// Multiple integers on one line
val (a, b, c) = readLine()!!.split(" ").map { it.toInt() }
// List of integers
val values = readLine()!!.split(" ").map { it.toInt() }
// Multiple lines
val data = List(n) { readLine()!!.toInt() }
The !! operator asserts that readLine() is not null. This is safe for competitive programming where input format is guaranteed.
Writing Output
// Single value
println(result)
// Multiple values
println("$a $b $c")
// Formatted
println("%.2f".format(pi))
Common Functions
Min/Max
val maxValue = maxOf(a, b)
val minValue = minOf(a, b)
// Or using coerceAtLeast/coerceAtMost
val max = a.coerceAtLeast(b)
val min = a.coerceAtMost(b)
Collections
// List
val list = listOf(1, 2, 3)
val mutableList = mutableListOf(1, 2, 3)
// Array
val arr = Array(n) { 0 }
val intArr = IntArray(n) { 0 }
// Map operations
val doubled = list.map { it * 2 }
val filtered = list.filter { it > 0 }
val sum = list.sum()
Kotlin Features for Competitive Programming
Range Iterations
// Inclusive range
for (i in 0..n-1) { }
for (i in 0 until n) { } // Exclusive end
// Reverse
for (i in n-1 downTo 0) { }
// With step
for (i in 0..n step 2) { }
Pair and Triple
val pair = Pair(1, 2)
val (x, y) = pair
val triple = Triple(1, 2, 3)
val (a, b, c) = triple
Lambda Functions
val max = { a: Int, b: Int -> if (a > b) a else b }
println(max(5, 3))
Kotlin’s concise syntax and powerful standard library functions can significantly reduce code length in competitive programming.
Kotlin compiles to JVM bytecode like Java, so performance is generally comparable. However, compilation time can be slower than Java.
Fast I/O
For large inputs, consider using BufferedReader:
import java.io.BufferedReader
import java.io.InputStreamReader
fun main() {
val reader = BufferedReader(InputStreamReader(System.`in`))
val n = reader.readLine().toInt()
val values = reader.readLine().split(" ").map { it.toInt() }
// Your code here
}
Comparison with Java
Kotlin offers several advantages over Java for competitive programming:
- More concise syntax
- Null safety with
!! and ? operators
- Extension functions and operators
- Built-in collection operations (map, filter, etc.)
- Type inference
- Linux: Full support
- Windows: Full support
- macOS: Full support