Added some algorithms and moved some files and fixed some comments

src/zutil/algo/search/QuickSelect.java

@@ -0,0 +1,68 @@
+package zutil.algo.search;
+
+import zutil.algo.sort.sortable.SortableDataList;
+
+/**
+ * This algorithm is a modified QuickSort 
+ * to find the k smallest or biggest value
+ * http://en.wikipedia.org/wiki/Selection_algorithm
+ * 
+ * @author Ziver
+ *
+ */
+@SuppressWarnings("unchecked")
+public class QuickSelect {
+	
+	public static Object find(SortableDataList list, int k){
+		return find(list, k, 0, list.size()-1);
+	}
+	
+	/*
+	 function select(list, k, left, right)
+	     select a pivot value list[pivotIndex]
+	     pivotNewIndex := partition(list, left, right, pivotIndex)
+	     if k = pivotNewIndex
+	         return list[k]
+	     else if k < pivotNewIndex
+	         return select(list, k, left, pivotNewIndex-1)
+	     else
+	         return select(list, k, pivotNewIndex+1, right)
+	 */
+	public static Object find(SortableDataList list, int k, int left, int right){
+		// select a pivot
+		int pivot = right/2;
+		int newPivot = partition(list, left, right, pivot);
+		if(k == newPivot)
+			return list.getIndex(k);
+		else if(k < newPivot)
+			return find(list, k, left, newPivot-1);
+		else
+			return find(list, k, newPivot+1, right);
+	}
+	
+	/*
+	 function partition(list, left, right, pivotIndex)
+	     pivotValue := list[pivotIndex]
+	     swap list[pivotIndex] and list[right]  // Move pivot to end
+	     storeIndex := left
+	     for i from left to right-1
+	         if list[i] < pivotValue
+	             swap list[storeIndex] and list[i]
+	             storeIndex := storeIndex + 1
+	     swap list[right] and list[storeIndex]  // Move pivot to its final place
+	     return storeIndex
+	 */
+	private static int partition(SortableDataList list, int left, int right, int pivot){
+		Object pivotValue = list.getIndex(pivot);
+		list.swap(pivot, right);
+		int storeIndex = left;
+		for(int i=left; i<right ;i++){
+			if(list.compare(i, pivotValue) < 0){
+				list.swap(storeIndex, i);
+				storeIndex = storeIndex+1;
+			}
+		}
+		list.swap(right, storeIndex);
+		return storeIndex;
+	}
+}