Data commit

Task/Modular-arithmetic/Kotlin/modular-arithmetic.kotlin

@@ -0,0 +1,41 @@
+// version 1.1.3
+
+interface Ring<T> {
+    operator fun plus(other: Ring<T>): Ring<T>
+    operator fun times(other: Ring<T>): Ring<T>
+    val value: Int
+    val one: Ring<T>
+}
+
+fun <T> Ring<T>.pow(p: Int): Ring<T> {
+    require(p >= 0)
+    var pp = p
+    var pwr = this.one
+    while (pp-- > 0) pwr *= this
+    return pwr
+}
+
+class ModInt(override val value: Int, val modulo: Int): Ring<ModInt> {
+
+    override operator fun plus(other: Ring<ModInt>): ModInt {
+        require(other is ModInt &&  modulo == other.modulo)
+        return ModInt((value + other.value) % modulo, modulo)
+    }
+
+    override operator fun times(other: Ring<ModInt>): ModInt {
+        require(other is ModInt && modulo == other.modulo)
+        return ModInt((value * other.value) % modulo, modulo)
+    }
+
+    override val one get() = ModInt(1, modulo)
+
+    override fun toString() = "ModInt($value, $modulo)"
+}
+
+fun <T> f(x: Ring<T>): Ring<T> = x.pow(100) + x + x.one
+
+fun main(args: Array<String>) {
+    val x = ModInt(10, 13)
+    val y = f(x)
+    println("x ^ 100 + x + 1 for x == ModInt(10, 13) is $y")
+}