Data commit

Task/Range-extraction/Swift/range-extraction.swift

@@ -0,0 +1,49 @@
+import Darwin
+
+func ranges(from ints:[Int]) -> [(Int, Int)] {
+
+	var range : (Int, Int)?
+	var ranges = [(Int, Int)]()
+	for this in ints {
+		if let (start, end) = range {
+			if this == end + 1 {
+				range = (start, this)
+			}
+			else {
+				ranges.append(range!)
+				range = (this, this)
+			}
+		}
+		else { range = (this, this) }
+	}
+	ranges.append(range!)
+
+	return ranges
+}
+
+func description(from ranges:[(Int, Int)]) -> String {
+	var desc = ""
+	for (start, end) in ranges {
+		desc += desc.isEmpty ? "" : ","
+		if start == end {
+			desc += "\(start)"
+		}
+		else if end == start + 1 {
+			desc += "\(start),\(end)"
+		}
+		else {
+			desc += "\(start)-\(end)"
+		}
+	}
+	return desc
+}
+
+
+let ex = [-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20]
+let longer = [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]
+
+print(description(from: ranges(from: ex)))
+print(description(from: ranges(from: longer)))