cyclic sort

Author: Dhananjay Nagargoje

Diff for: src/main/java/problems/patterns/cyclicsort/AllMissingNumbers.java

@@ -1,4 +1,39 @@
 package problems.patterns.cyclicsort;
+import java.util.*;
 
-public class AllMissingNumbers {
-}
+class AllMissingNumbers {
+
+    public static List<Integer> findNumbers(int[] nums) {
+        int i = 0;
+        while (i < nums.length) {
+            if (nums[i] != nums[nums[i] - 1])
+                swap(nums, i, nums[i] - 1);
+            else
+                i++;
+        }
+
+        List<Integer> missingNumbers = new ArrayList<>();
+        for (i = 0; i < nums.length; i++)
+            if (nums[i] != i + 1)
+                missingNumbers.add(i + 1);
+
+        return missingNumbers;
+    }
+
+    private static void swap(int[] arr, int i, int j) {
+        int temp = arr[i];
+        arr[i] = arr[j];
+        arr[j] = temp;
+    }
+
+    public static void main(String[] args) {
+        List<Integer> missing = AllMissingNumbers.findNumbers(new int[] { 2, 3, 1, 8, 2, 3, 5, 1 });
+        System.out.println("Missing numbers: " + missing);
+
+        missing = AllMissingNumbers.findNumbers(new int[] { 2, 4, 1, 2 });
+        System.out.println("Missing numbers: " + missing);
+
+        missing = AllMissingNumbers.findNumbers(new int[] { 2, 3, 2, 1 });
+        System.out.println("Missing numbers: " + missing);
+    }
+}

Diff for: src/main/java/problems/patterns/cyclicsort/CyclicSortBasic.java

@@ -1,4 +1,44 @@
-package problems.patterns.slidingwindows.cyclicsort;
+package problems.patterns.cyclicsort;
 
 public class CyclicSortBasic {
+
+
+    public static void sort(int[] nums) {
+      int i = 0;
+      while (i < nums.length) {
+          int j = nums[i] - 1;
+          if (nums[i] != nums[j]) {
+              swap(nums, i, j);
+          } else {
+              i++;
+          }
+      }
+    }
+
+    private static void swap(int[] arr, int i, int j) {
+        int temp = arr[i];
+        arr[i] = arr[j];
+        arr[j] = temp;
+    }
+
+    public static void main(String[] args) {
+        int[] arr = new int[] { 3, 1, 5, 4, 2 };
+        CyclicSortBasic.sort(arr);
+        for (int num : arr)
+            System.out.print(num + " ");
+        System.out.println();
+
+        arr = new int[] { 2, 6, 4, 3, 1, 5 };
+        CyclicSortBasic.sort(arr);
+        for (int num : arr)
+            System.out.print(num + " ");
+        System.out.println();
+
+        arr = new int[] { 1, 5, 6, 4, 3, 2 };
+        CyclicSortBasic.sort(arr);
+        for (int num : arr)
+            System.out.print(num + " ");
+        System.out.println();
+    }
 }
+

Diff for: src/main/java/problems/patterns/cyclicsort/FindDuplicate.java

@@ -1,4 +1,31 @@
 package problems.patterns.cyclicsort;
+class FindDuplicate {
 
-public class FindDuplicate {
-}
+    public static int findNumber(int[] nums) {
+        int i = 0;
+        while (i < nums.length) {
+            if (nums[i] != i + 1) {
+                if (nums[i] != nums[nums[i] - 1])
+                    swap(nums, i, nums[i] - 1);
+                else // we have found the duplicate
+                    return nums[i];
+            } else {
+                i++;
+            }
+        }
+
+        return -1;
+    }
+
+    private static void swap(int[] arr, int i, int j) {
+        int temp = arr[i];
+        arr[i] = arr[j];
+        arr[j] = temp;
+    }
+
+    public static void main(String[] args) {
+        System.out.println(FindDuplicate.findNumber(new int[] { 1, 4, 4, 3, 2 }));
+        System.out.println(FindDuplicate.findNumber(new int[] { 2, 1, 3, 3, 5, 4 }));
+        System.out.println(FindDuplicate.findNumber(new int[] { 2, 4, 1, 4, 4 }));
+    }
+}

Diff for: src/main/java/problems/patterns/cyclicsort/MissingNumber.java

@@ -1,4 +1,35 @@
 package problems.patterns.cyclicsort;
 
-public class MissingNumber {
-}
+class MissingNumber {
+
+    public static int findMissingNumber(int[] nums) {
+
+        int i = 0 ;
+        while (i < nums.length) {
+            if (nums[i] != nums.length
+                    && nums[i] != nums[nums[i]]) {
+                swap(nums, i ,  nums[i]);
+            } else {
+                i++;
+            }
+        }
+        for (int k=0;k < nums.length;k++) {
+            if (nums[k] != k) {
+                return k;
+            }
+        }
+
+        return nums.length;
+    }
+
+    private static void swap(int[] arr, int i, int j) {
+        int temp = arr[i];
+        arr[i] = arr[j];
+        arr[j] = temp;
+    }
+
+    public static void main(String[] args) {
+        System.out.println(MissingNumber.findMissingNumber(new int[] { 4, 0, 3, 1 }));
+        System.out.println(MissingNumber.findMissingNumber(new int[] { 8, 3, 5, 2, 4, 6, 0, 1 }));
+    }
+}