day2: array manipulation 1

Basic/TotalNumberOfParirsWhoseSumIsEqualToX.java

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+// write a code in java to find the total number of pairs whose sum is equal to a given number using function
+import java.util.Scanner;
+class TotalNumberOfParirsWhoseSumIsEqualToX{
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        System.out.println("Enter the size of the array");
+        int n = sc.nextInt();
+        int[] arr = new int[n];
+        System.out.println("Enter the elements of the array");
+        for(int i=0;i<n;i++){
+            arr[i] = sc.nextInt();
+        }
+        System.out.println("Enter the value of x");
+        int x = sc.nextInt();
+        System.out.println("The total number of pairs whose sum is equal to "+x+" is "+totalPairs(arr,n,x));
+        sc.close();
+    }
+    public static int totalPairs(int[] arr,int n,int x){
+        int count = 0;
+        for(int i=0;i<n;i++){
+            for(int j=i+1;j<n;j++){
+                if(arr[i]+arr[j]==x){
+                    count++;
+                }
+            }
+        }
+        return count;
+    }
+}

Basic/TotalNumberOfTripletsWhoseSumIsEqualToX.java

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+// write a code in java to find the total number of triplets whose sum is equal to a given number using function
+import java.util.Scanner;
+class TotalNumberOfTripletsWhoseSumIsEqualToX{
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        System.out.println("Enter the size of the array");
+        int n = sc.nextInt();
+        int arr[] = new int[n];
+        System.out.println("Enter the elements of the array");
+        for(int i=0;i<n;i++){
+            arr[i] = sc.nextInt();
+        }
+        System.out.println("Enter the value of x");
+        int x = sc.nextInt();
+        System.out.println("The total number of triplets whose sum is equal to "+x+" is "+countTriplets(arr,n,x));
+        sc.close();
+    }
+
+    static int countTriplets(int arr[],int n,int x){
+        int count = 0;
+        for(int i=0;i<n-2;i++){
+            for(int j=i+1;j<n-1;j++){
+                for(int k=j+1;k<n;k++){
+                    if(arr[i]+arr[j]+arr[k]==x){
+                        count++;
+                    }
+                }
+            }
+        }
+        return count;
+    }
+}

Basic/UniqueArrayElement.java

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+// find the unique number in a givern array wherer all the elements are being twive with one value being unique using function
+
+import java.util.Scanner;
+class UniqueArrayElement{
+    public static void main(String[] args){
+        Scanner sc = new Scanner(System.in);
+        System.out.println("Enter the number of elements in the array");
+        int n = sc.nextInt();
+        int[] arr = new int[n];
+        System.out.println("Enter the elements of the array");
+        for(int i=0;i<n;i++){
+            arr[i] = sc.nextInt();
+        }
+        System.out.println("The unique element in the array is "+findUnique(arr));
+    }
+    public static int findUnique(int[] arr){
+        int res = 0;
+        for(int i=0;i<arr.length;i++){
+            res = res^arr[i];
+        }
+        return res;
+    }
+
+    // dry run: 
+    // arr = [1,2,3,4,1,2,3]
+    // res = 0
+    // res = 0^1 = 1
+    // res = 1^2 = 3
+    // res = 3^3 = 0
+    // res = 0^4 = 4
+    // res = 4^1 = 5
+    // res = 5^2 = 7
+    // res = 7^3 = 4
+    // return 4
+
+}