Data commit

Task/Pascal-matrix-generation/Kotlin/pascal-matrix-generation.kotlin

@@ -0,0 +1,32 @@
+// version 1.1.3
+
+fun binomial(n: Int, k: Int): Int {
+    if (n < k) return 0
+    if (n == 0 || k == 0) return 1
+    val num = (k + 1..n).fold(1) { acc, i -> acc * i }
+    val den = (2..n - k).fold(1) { acc, i -> acc * i }
+    return num / den
+}
+
+fun pascalUpperTriangular(n: Int) = List(n) { i -> IntArray(n) { j -> binomial(j, i) } }
+
+fun pascalLowerTriangular(n: Int) = List(n) { i -> IntArray(n) { j -> binomial(i, j) } }
+
+fun pascalSymmetric(n: Int)       = List(n) { i -> IntArray(n) { j -> binomial(i + j, i) } }
+
+fun printMatrix(title: String, m: List<IntArray>) {
+    val n = m.size
+    println(title)
+    print("[")
+    for (i in 0 until n) {
+        if (i > 0) print(" ")
+        print(m[i].contentToString())
+        if (i < n - 1) println(",") else println("]\n")
+    }
+}
+
+fun main(args: Array<String>) {
+    printMatrix("Pascal upper-triangular matrix", pascalUpperTriangular(5))
+    printMatrix("Pascal lower-triangular matrix", pascalLowerTriangular(5))
+    printMatrix("Pascal symmetric matrix", pascalSymmetric(5))
+}