Data commit

Task/Fusc-sequence/Go/fusc-sequence.go

@@ -0,0 +1,70 @@
+package main
+
+import (
+    "fmt"
+    "strconv"
+)
+
+func fusc(n int) []int {
+    if n <= 0 {
+        return []int{}
+    }
+    if n == 1 {
+        return []int{0}
+    }
+    res := make([]int, n)
+    res[0] = 0
+    res[1] = 1
+    for i := 2; i < n; i++ {
+        if i%2 == 0 {
+            res[i] = res[i/2]
+        } else {
+            res[i] = res[(i-1)/2] + res[(i+1)/2]
+        }
+    }
+    return res
+}
+
+func fuscMaxLen(n int) [][2]int {
+    maxLen := -1
+    maxFusc := -1
+    f := fusc(n)
+    var res [][2]int
+    for i := 0; i < n; i++ {
+        if f[i] <= maxFusc {
+            continue // avoid expensive strconv operation where possible
+        }
+        maxFusc = f[i]
+        le := len(strconv.Itoa(f[i]))
+        if le > maxLen {
+            res = append(res, [2]int{i, f[i]})
+            maxLen = le
+        }
+    }
+    return res
+}
+
+func commatize(n int) string {
+    s := fmt.Sprintf("%d", n)
+    if n < 0 {
+        s = s[1:]
+    }
+    le := len(s)
+    for i := le - 3; i >= 1; i -= 3 {
+        s = s[0:i] + "," + s[i:]
+    }
+    if n >= 0 {
+        return s
+    }
+    return "-" + s
+}
+
+func main() {
+    fmt.Println("The first 61 fusc numbers are:")
+    fmt.Println(fusc(61))
+    fmt.Println("\nThe fusc numbers whose length > any previous fusc number length are:")
+    res := fuscMaxLen(20000000)  // examine first twenty million numbers say
+    for i := 0; i < len(res); i++ {
+        fmt.Printf("%7s (index %10s)\n", commatize(res[i][1]), commatize(res[i][0]))
+    }
+}