// remove duplicate from an array using set
int[] ar = { 1, 1, 2, 3, 4, 5, 6, 6, 7, 8 };
Set<Integer> uniqueElements = new HashSet<>();
for (int i = 0; i < ar.length; i++) {
uniqueElements.add(ar[i]);
}
for (Integer i : uniqueElements) {
System.out.print(i+" ");
}
//Using HashMap
Map<Integer, Integer> uniqueElements = new HashMap<>();
for (int i = 0; i < ar.length; i++) {
if (uniqueElements.get(ar[i]) == null) {
System.out.print(ar[i] + " ");
uniqueElements.put(ar[i], ar[i]);
}
}
int f1 = 0, f2 = 1;
int f3 = 0;
System.out.print(f1+" ");
System.out.print(f2+" ");
for (int i = 1; i <=8; i++) {
f3 = f1 + f2;
System.out.print(f3+" ");
f1 = f2;
f2 = f3;
}
package arrayoperations;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
public class MainApp {
public static void main(String[] args) {
int[] a = { 1, 2, 2, 3, 4, 4, 4 };
Map<Integer, Integer> frequency = new HashMap();
for (int i = 0; i < a.length; i++) {
if (frequency.containsKey(a[i])) {
frequency.put(a[i], frequency.get(a[i]) + 1);
} else {
frequency.put(a[i], 1);
}
}
Set<Integer> keySet = frequency.keySet();
for(Integer i: keySet) {
System.out.println("item: "+ i+ " frequency: "+frequency.get(i));
}
}
}
public class SinglyLinkedList {
private ListNode head;
private static class ListNode {
private int data;
private ListNode next;
public ListNode(int data) {
this.data = data;
this.next = null;
}
}
// printing singly linked list
public void displayList(ListNode head) {
ListNode current = head;
while (current != null) {
System.out.println(current.data);
current = current.next;
}
}
// Reverse the linked list
public ListNode reverse(ListNode head) {
if (head == null) {
return head;
}
ListNode current = head;
ListNode previous = null;
ListNode next = null;
while (current != null) {
next = current.next;
current.next = previous;
previous = current;
current = next;
}
return previous;
}
public static void main(String[] args) {
// creating nodes
SinglyLinkedList sl = new SinglyLinkedList();
sl.head = new ListNode(10);
ListNode second = new ListNode(1);
ListNode third = new ListNode(2);
ListNode fourth = new ListNode(3);
// connecting nodes together
sl.head.next = second;
second.next = third;
third.next = fourth;
fourth.next = null;
sl.displayList(sl.head);
SinglyLinkedList.ListNode reverse = sl.reverse(sl.head);
sl.displayList(reverse);
}
}
String input = "geeksforgeeks";
char[] inputAr = input.toCharArray();
char temp;
for (int i = 0; i < inputAr.length ; i++) {// no of pass controller
for (int j = 0; j < inputAr.length -i- 1; j++) {
if (inputAr[j] > inputAr[j+1]) { //comparing with adjacent character.
temp = inputAr[j];
inputAr[j] = inputAr[j+1];
inputAr[j+1] = temp;
}
}
}
for (int i = 0; i < inputAr.length ; i++) {
System.out.println(inputAr[i]);
}
Here we apply recursion because our array contains another array .so the process of addition is same as the outer array .
public class MainApp {
public static void main(String[] args) {
List<Object> a1 = new ArrayList<Object>();
a1.add(1);
a1.add(2);
a1.add(3);
a1.add(4);
List<Object> a2 = new ArrayList<Object>();
a2.add(5);
a2.add(6);
a2.add(7);
List<Object> arrays = new ArrayList<Object>();
arrays.addAll(a1);
arrays.add(a2);
arrays.add(8);
arrays.add(9);
int result = productSum(arrays, 1);
System.out.println(result);
}
public static int productSum(List<Object> inputs, int depth) {
int sum = 0;
for (Object obj : inputs) {
if (obj instanceof List) {
sum += productSum((List<Object>) obj, depth + 1);
} else {
sum += (int) obj;
}
}
return sum * depth;
}
}
public class MainApp {
public static void main(String[] args) {
String input = "aabbbcccdeefghijkkkkkk";
calculateFrequency(input);
}
private static void calculateFrequency(String input) {
Map<Character, Integer> frequency = new HashMap();
for (int i = 0; i < input.length(); i++) {
if (frequency.containsKey(input.charAt(i))) {
frequency.put(input.charAt(i), frequency.get(input.charAt(i)) + 1);
} else {
frequency.put(input.charAt(i), 1);
}
}
Set<Character> keySet = frequency.keySet();
for (Character c : keySet) {
System.out.println(c + ":" + frequency.get(c));
}
}
}
