FindMissing added

src/main/java/ua/com/florin/Runner.java

@@ -3,13 +3,23 @@
 import main.java.ua.com.florin.customlist.CustomList;
 import main.java.ua.com.florin.substring.SubStringer;
 
+import java.util.LinkedList;
+import java.util.List;
+
 /**
  * Created by florin on 19.07.2014.
  */
 public class Runner {
 
     public static void main(String[] args) {
+        List<String> stringList = new LinkedList<String>();
+        for (int i = 0; i < 10; i++) {
+            stringList.add("test " + i);
+        }
+        System.out.println(stringList);
 
+        stringList.subList(0, 5).clear();
+        System.out.println(stringList);
     }
 
 }

src/main/java/ua/com/florin/algorithm/Sorter.java

@@ -0,0 +1,93 @@
+package main.java.ua.com.florin.algorithm;
+
+/**
+ * Contains static methods with custom realizations of different sorting algorithms for sorting an array
+ * <p/>
+ * Created by florin on 06.08.2014.
+ */
+public class Sorter {
+
+    /**
+     *
+     * @param a target array
+     */
+    public static void sortByInsertion(int[] a) {
+        for (int i = 1; i < a.length; i++) {
+            for (int j = i; j > 0 && a[j] < a[j - 1]; j--) {
+                swap(a, j, j - 1);
+            }
+        }
+    }
+
+    /**
+     *
+     * @param a target array
+     */
+    public static void sortBySelection(int[] a) {
+        for (int i = 1; i < a.length - 1; i++) {
+            for (int j = i + 1; j < a.length; j++) {
+                if (a[j] < a[i]) {
+                    swap(a, i, j);
+                }
+            }
+        }
+    }
+
+    /**
+     *
+     * @param a target array
+     */
+    public static void sortByBubble(int[] a) {
+        for (int i = 0; i < a.length; i++) {
+            for (int j = 0; j < a.length - i - 1; j++) {
+                if (a[j] > a[j + 1]) {
+                    swap(a, j, j + 1);
+                }
+            }
+        }
+    }
+
+    /**
+     *
+     * @param a target array
+     * @param low
+     * @param high
+     */
+    public static void sortByQuick(int[] a, int low, int high) {
+        int i = low;
+        int j = high;
+        int pivot = a[a.length / 2];
+        while (i <= j) {
+            while (a[i] < pivot) {
+                i++;
+            }
+            while (a[j] > pivot) {
+                j--;
+            }
+            if (i <= j) {
+                swap(a, i, j);
+                i++;
+                j--;
+            }
+        }
+        if (low < j) {
+            sortByQuick(a, low, j);
+        }
+        if (i < high) {
+            sortByQuick(a, i, high);
+        }
+    }
+
+    /**
+     * Swaps the elements in the given array
+     *
+     * @param a target array
+     * @param i first element to be swapped
+     * @param j second element to be swapped
+     */
+    private static void swap(int[] a, int i, int j) {
+        int tmp = a[i];
+        a[i] = a[j];
+        a[j] = tmp;
+    }
+}

src/main/java/ua/com/florin/findmissing/FindMissing.java

@@ -0,0 +1,39 @@
+package main.java.ua.com.florin.findmissing;
+
+/**
+ * Created by florin on 06.08.2014.
+ */
+public class FindMissing {
+
+    /**
+     * Finds the missing number in the array of consecutive numbers
+     *
+     * @param a an array with consecutive numbers with one missing
+     * @return the missing number
+     */
+    public static int findMissing(int[] a) {
+
+        // sum of all elements in the array
+        int fullSum = 0;
+        // number of elements in the array, supposing that one is missing
+        int fullLen = a.length + 1;
+
+        // calculating the sum of the array's elements
+        for (int i = 1; i <= fullLen; i++) {
+            fullSum += i;
+        }
+
+        // sum of the actual elements in the array
+        int partSum = 0;
+        // actual length of the array
+        int partLen = a.length;
+
+        // calculating the sum of actual array's elements
+        for (int elem : a) {
+            partSum += elem;
+        }
+
+        // the missing element will be equal to the difference between two calculated sums
+        return fullSum - partSum;
+    }
+}

src/main/java/ua/com/florin/substring/SubStringer.java

@@ -1,11 +1,21 @@
 package main.java.ua.com.florin.substring;
 
 /**
+ * Contains custom realizations of substring methods for the sake of practice
+ * <p/>
  * Created by florin on 20.07.2014.
  */
 public class SubStringer {
 
+    /**
+     * Returns the substring beginning from the given start position inclusively
+     *
+     * @param string   target string for getting the substring
+     * @param startPos start position from which to get the substring (inclusively)
+     * @return substring from startPos inclusively
+     */
     public static String mySubString(String string, int startPos) {
+
         // create char array from target string
         char[] stringArray = string.toCharArray();
 
@@ -32,6 +42,14 @@ public static String mySubString(String string, int startPos) {
         return new String(subStringArray);
     }
 
+    /**
+     * Returns the substring beginning from the given start position inclusively and endPosition exclusively
+     *
+     * @param string   target string for getting the substring
+     * @param startPos start position from which to get the substring (inclusively)
+     * @param endPos   end position to which to get the substring (exclusively)
+     * @return substring from startPos inclusively and endPos exclusively
+     */
     public static String mySubString(String string, int startPos, int endPos) {
         // create char array from target string
         char[] stringArray = string.toCharArray();

src/test/java/FindMissingTest.java

@@ -0,0 +1,29 @@
+package test.java;
+
+import main.java.ua.com.florin.findmissing.FindMissing;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+
+public class FindMissingTest {
+
+    int[] array = {1, 2, 3, 4, 5, 6, 7, 8, 10};
+
+    @Before
+    public void setUp() throws Exception {
+    }
+
+    @After
+    public void tearDown() throws Exception {
+        array = null;
+    }
+
+    @Test
+    public void testFindMissing() throws Exception {
+        assertEquals(9, FindMissing.findMissing(array));
+        assertNotEquals(10, FindMissing.findMissing(array));
+    }
+}