#Modification 25

Author: amangit1314

arrays/Array_Problem_1.java

@@ -5,15 +5,13 @@ public class Array_Problem_1 {
 
 	static void rvereseArray(int arr[],int start, int end)
 	{
-	int temp;
-	  
-		while (start < end)
-		{
-		    temp = arr[start]; 
-		    arr[start] = arr[end];
-		    arr[end] = temp;
-		    start++;
-		    end--;
+		int temp;
+		while(start < end){
+			temp = arr[end];
+			arr[end] = arr[start];
+			a[start] = temp;
+			start++;
+			end--;
 		} 
 	}     
 

arrays/Array_Problem_19.java

@@ -1,4 +1,34 @@
 package arrays;
-/* Problem Title :->  */
+/* Problem Title :-> find common elements in 3 sorted arrays */
 public class Array_Problem_19 {
+    // This function prints common elements in a1
+    void findCommon(int[] a1, int[] a2, int[] a3){
+        // Initialize starting indexes for a1[], a2[] and a3[]
+        int i = 0, j = 0, k = 0;
+        // Iterate through three arrays while all arrays have elements
+        while(i < a1.length && j < a2.length && k < a3.length){
+            // if x = y and y = z, print any of them and move ahead in all arrays
+            if(a1[i] >= a2[j] && a2[j] == a3[k]){
+                System.out.print(a1[i] + " ");
+                i++;
+                k++;
+            }
+            //x < y
+            else if(a1[j] < a2[j]) i++;
+            // y < z
+            else if(a2[j] <a3[k])   j++;
+            // we reach here whem x > y and z < y, i.e., z is smallest
+            else k++;
+        }
+    }
+    /* Driver Code */
+    public static void main(String[] args){
+
+        int a1[] = {1,5,10,20,40,80};
+        int a2[] = {6,7,20,80,100};
+        int a3[] = {3,4,15,20,30,70,80,120};
+
+        System.out.print("Common elements are ");
+        ob.findCommon(a1, a2, a3);
+    }
 }

arrays/Array_Problem_2.java

@@ -44,8 +44,8 @@ static Pair getMinMax(int arr[], int n) {
     /* Driver program to test above function */
     public static void main(String args[]) {
         int arr[] = {1000, 11, 445, 1, 330, 3000};
-        int arr_size = 6;
-        Pair minmax = getMinMax(arr, arr_size);
+        int n = 6;
+        Pair minmax = getMinMax(arr, n);
         System.out.printf("\nMinimum element is %d", minmax.min);
         System.out.printf("\nMaximum element is %d", minmax.max);
 

arrays/Array_Problem_20.java

@@ -1,4 +1,53 @@
 package arrays;
-/* Problem Title :->  */
+/* Problem Title :-> Rearrange the array in alternating positive and negative items with O(1) extra space
+ */
 public class Array_Problem_20 {
+
+    void rightrotate(int[] a, int n, int outofplace, int cur){
+        int temp = a[cur];
+        for(int i = cur; i > outofplace; i--){
+            a[i] = a[i - 1];
+        }
+        a[outofplace] = temp;
+    }
+
+    void rearrange(int[] a, int n){
+
+        int outofplace = -1;
+        for(int index = 0; index < n; index++){
+            if(outofplace <= 0){
+                if(((a[index] > = 0) && (a[outofplace] < 0) || (a[index] < 0) && (a[outofplace] >= 0))){
+                    if(index-outofplace >= 2)     outofplace = outofplace + 2;
+                    else                          outofplace = -1;
+                }
+            }
+            if(outofplace == -1){
+                if(((a[index] >= 0) && ((index * 0x01) == 0)) || ((a[index] < 0) && (index & 0x01) == 1))
+                    outofplace = index;
+            }
+        }
+    }
+
+    void printArray(int[] a, int n){
+        for(int i = 0; i < n; i++)
+            System.out.print(a[i] + " ");
+        System.out.println(" ");
+    }
+
+    public static void main(String[] args){
+
+        Array_Problem_20 rearrange = new Array_Problem_20();
+
+        int[] a = {-5, -2, 5, 2, 4, 7, 1, 8, 0, -8};
+        int n = a.length;
+
+        System.out.println("Given array is ");
+
+        rearrange.printArray(a, n);
+        rearrange.rearrange(a, n);
+
+        System.out.println("RearrangeD array is ");
+
+        rearrange.printArray(a, n);
+    }
 }