Merge pull request #625 from jakecast/patch-1

update to radix sort

Author: kelvinlauKL

Radix Sort/radixSort.swift

@@ -5,43 +5,35 @@
 */
 
 
-func radixSort(inout arr: [Int] ) {
-
-
-  let radix = 10  //Here we define our radix to be 10
-  var done = false
-  var index: Int
-  var digit = 1  //Which digit are we on?
-
-
-  while !done {  //While our  sorting is not completed
-    done = true  //Assume it is done for now
-
-    var buckets: [[Int]] = []  //Our sorting subroutine is bucket sort, so let us predefine our buckets
-
-    for _ in 1...radix {
-      buckets.append([])
-    }
-
-
-    for number in arr {
-      index = number / digit  //Which bucket will we access?
-      buckets[index % radix].append(number)
-      if done && index > 0 {  //If we arent done, continue to finish, otherwise we are done
-        done = false
-      }
-    }
-
-    var i = 0
-
-    for j in 0..<radix {
-      let bucket = buckets[j]
-      for number in bucket {
-        arr[i] = number
-        i += 1
-      }
-    }
-
-    digit *= radix  //Move to the next digit
-  }
+func radixSort(arr: inout [Int]) {
+    let radix = 10
+
+    var digit: Int = 1
+    var largest: Int = 0
+
+    var buckets: [[Int]]
+    var index: Int
+    var pos: Int
+
+    repeat {
+        pos = 0
+        buckets = Array(repeatElement([], count: 10))
+
+        for num in arr {
+            index = num / digit
+            buckets[index % radix].append(num)
+
+            if digit == 1 {
+                largest = max(largest, num)
+            }
+        }
+        for bin in buckets {
+            for num in bin {
+                arr[pos] = num
+                pos = pos + 1
+            }
+        }
+
+        digit = digit * radix
+    } while digit < largest
 }