Merge pull request #74 from KuLi/cycleSort

Implemented cycle sort algorithm

Author: ms10398

Sorts/cycleSort.js

@@ -0,0 +1,62 @@
+/* 
+Wikipedia says: Cycle sort is an in-place, unstable sorting algorithm, 
+a comparison sort that is theoretically optimal in terms of the total 
+number of writes to the original array, unlike any other in-place sorting 
+algorithm. It is based on the idea that the permutation to be sorted can 
+be factored into cycles, which can individually be rotated to give a sorted result.
+*/
+function cycleSort(list) {
+
+    let writes = 0;
+    for (let cycleStart = 0; cycleStart < list.length; cycleStart++) {
+
+        let value = list[cycleStart];
+        let position = cycleStart;
+
+        // search position
+        for (let i = cycleStart+1; i < list.length; i++) {
+
+            if (list[i] < value) {
+                position++;
+            }
+        }
+        // if its the same continue
+        if (position == cycleStart) {
+            continue;
+        }
+
+        while (value == list[position]) {
+            position++;
+        }
+
+        let oldValue = list[position];
+        list[position] = value;
+        value = oldValue;
+        writes++;
+
+        // rotate the rest
+        while (position != cycleStart) {
+            position = cycleStart;
+            for (let i = cycleStart +1; i < list.length; i++) {
+
+                if (list[i] < value) {
+                    position++;
+                }
+            }
+            while (value == list[position]) {
+                position++;
+            }
+            let oldValueCycle = list[position];
+            list[position] = value;
+            value = oldValueCycle;
+            writes++;
+        }
+    }
+    return writes;
+}
+let arrOrignal = [5, 6, 7, 8, 1, 2,12, 14];
+//Array before Sort
+console.log(arrOrignal);
+cycleSort(arrOrignal);
+//Array after sort
+console.log(arrOrignal);