Data commit

Task/Fusc-sequence/Kotlin/fusc-sequence.kotlin

@@ -0,0 +1,43 @@
+// Version 1.3.21
+
+fun fusc(n: Int): IntArray {
+    if (n <= 0) return intArrayOf()
+    if (n == 1) return intArrayOf(0)
+    val res = IntArray(n)
+    res[1] = 1
+    for (i in 2 until n) {
+        if (i % 2 == 0) {
+            res[i] = res[i / 2]
+        } else {
+            res[i] = res[(i - 1) / 2] + res[(i + 1) / 2]
+        }
+    }
+    return res
+}
+
+fun fuscMaxLen(n: Int): List<Pair<Int, Int>> {
+    var maxLen = -1
+    var maxFusc = -1
+    val f = fusc(n)
+    val res = mutableListOf<Pair<Int, Int>>()
+    for (i in 0 until n) {
+        if (f[i] <= maxFusc) continue // avoid string conversion
+        maxFusc = f[i]
+        val len = f[i].toString().length
+        if (len > maxLen) {
+            res.add(Pair(i, f[i]))
+            maxLen = len
+        }
+    }
+    return res
+}
+
+fun main() {
+    println("The first 61 fusc numbers are:")
+    println(fusc(61).asList())
+    println("\nThe fusc numbers whose length > any previous fusc number length are:")
+    val res = fuscMaxLen(20_000_000)  // examine first 20 million numbers say
+    for (r in res) {
+        System.out.printf("%,7d (index %,10d)\n", r.second, r.first)
+    }
+}