Data commit

Task/Range-extraction/Go/range-extraction.go

@@ -0,0 +1,55 @@
+package main
+
+import (
+    "errors"
+    "fmt"
+    "strconv"
+    "strings"
+)
+
+func main() {
+    rf, err := rangeFormat([]int{
+        0, 1, 2, 4, 6, 7, 8, 11, 12, 14,
+        15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
+        25, 27, 28, 29, 30, 31, 32, 33, 35, 36,
+        37, 38, 39,
+    })
+    if err != nil {
+        fmt.Println(err)
+        return
+    }
+    fmt.Println("range format:", rf)
+}
+
+func rangeFormat(a []int) (string, error) {
+    if len(a) == 0 {
+        return "", nil
+    }
+    var parts []string
+    for n1 := 0; ; {
+        n2 := n1 + 1
+        for n2 < len(a) && a[n2] == a[n2-1]+1 {
+            n2++
+        }
+        s := strconv.Itoa(a[n1])
+        if n2 == n1+2 {
+            s += "," + strconv.Itoa(a[n2-1])
+        } else if n2 > n1+2 {
+            s += "-" + strconv.Itoa(a[n2-1])
+        }
+        parts = append(parts, s)
+        if n2 == len(a) {
+            break
+        }
+        if a[n2] == a[n2-1] {
+            return "", errors.New(fmt.Sprintf(
+                "sequence repeats value %d", a[n2]))
+        }
+        if a[n2] < a[n2-1] {
+            return "", errors.New(fmt.Sprintf(
+                "sequence not ordered: %d < %d", a[n2], a[n2-1]))
+        }
+        n1 = n2
+    }
+    return strings.Join(parts, ","), nil
+}