Data Structures
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Kunwar
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package arrays;
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import java.util.Arrays;
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public class MyDynamicArray {
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private int array[];
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private int size;
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private int capacity;
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/**
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* Constructor with initial capacity of 2
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*/
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public MyDynamicArray(){
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array = new int[2];
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size=0;
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capacity=2;
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}
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/**
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* check for capacity and if there is capacity add the element at the end of the array.
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* @param element
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*/
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public void addElement(int element){
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if (size == capacity){
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try{
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increaseCapacity(2);
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}catch(Exception e){
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System.out.println("unable to increase the capacity of the array");
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e.printStackTrace();
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}
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}
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array[size++] = element;
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}
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/**
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* Adding element at a given index
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* @param index
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* @param element
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*/
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public void addElement(int index, int element){
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//check if the array has capacity to add element.
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if (size == capacity){
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try{
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increaseCapacity(2);
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}catch(Exception e){
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System.out.println("unable to increase the capacity of the array");
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e.printStackTrace();
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}
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}
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// shift all elements from the given index to right
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for(int i=size-1;i>=index;i--){
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array[i+1] = array[i];
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}
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// insert the element at the specified index
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array[index] = element;
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size++;
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}
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/**
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* get an element from given index, O(1) time complexity
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* @param index
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* @return
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*/
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public int getElement(int index){
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return array[index];
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}
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/**
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* Remove an element at the last index
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*/
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public void remove(){
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if(size>1){
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array[size--]=0;
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}
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}
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/**
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* Remove an element from given index
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* @param index
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*/
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public void removeAt(int index){
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if(index>=size || index<0){
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System.out.println("No element at this index");
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}else{//shifting
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for(int i=index;i<size-1;i++){
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array[i] = array[i+1];
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}
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array[size-1]=0;
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size--;
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}
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}
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/**
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* If there is no place to insert a new element,
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* double the capacity for the array by creating
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* a new array and copy exiting elements.
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* @param minCapacity
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*/
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public void increaseCapacity(int minCapacity){
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int tempArray[] = new int[capacity*minCapacity];
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for (int i=0; i < capacity; i++){
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tempArray[i] = array[i];
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}
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array = tempArray;
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capacity = capacity * minCapacity;
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}
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/*
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* Trim the capacity of dynamic array to the current size. i.e. remove unused space
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*/
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public void trimToSize(){
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System.out.println("Trimming the array");
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int tempArray[] = new int[size];
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//we can use libraries as well to copy the array elements to temparray.
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for (int i=0; i < size; i++){
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tempArray[i] = array[i];
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}
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array = tempArray;
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capacity = array.length;
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}
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/**
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* return the size of the array
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* @return
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*/
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public int getSize(){
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return this.size;
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}
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/**
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* return the capacity of the array
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* @return
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*/
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public int getCapacity(){
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return this.capacity;
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}
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/**
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* Print the array elements
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*/
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public void printElements(){
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System.out.println("elements in array are :"+ Arrays.toString(array));
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}
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/**
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* main method
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* @param args
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*/
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public static void main(String args[]){
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MyDynamicArray array = new MyDynamicArray();
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// adding two elements to the array
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array.addElement(1);
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array.addElement(2);
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System.out.println("The array size is :"+array.getSize() + " and the array capacity is :"+array.getCapacity());
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array.addElement(3);
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System.out.println("The array size is :"+array.getSize() + " and the array capacity is :"+array.getCapacity());
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array.printElements();
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// add element at index 1
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array.addElement(1,5);
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System.out.println("The array size is :"+array.getSize() + " and the array capacity is :"+array.getCapacity());
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array.printElements();
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// add element at index 2
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array.addElement(2,6);
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System.out.println("The array size is :"+array.getSize() + " and the array capacity is :"+array.getCapacity());
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array.printElements();
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array.removeAt(2);
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System.out.println("The array size is :"+array.getSize() + " and the array capacity is :"+array.getCapacity());
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array.printElements();
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array.removeAt(2);
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System.out.println("The array size is :"+array.getSize() + " and the array capacity is :"+array.getCapacity());
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array.printElements();
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array.removeAt(1);
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System.out.println("The array size is :"+array.getSize() + " and the array capacity is :"+array.getCapacity());
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array.printElements();
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array.removeAt(2);
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System.out.println("The array size is :"+array.getSize() + " and the array capacity is :"+array.getCapacity());
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array.printElements();
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array.removeAt(1);
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System.out.println("The array size is :"+array.getSize() + " and the array capacity is :"+array.getCapacity());
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array.printElements();
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// Trim the array
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array.trimToSize();
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System.out.println("The array size is :"+array.getSize() + " and the array capacity is :"+array.getCapacity());
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array.printElements();
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array.addElement(2);
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System.out.println("The array size is :"+array.getSize() + " and the array capacity is :"+array.getCapacity());
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array.printElements();
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array.addElement(3);
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System.out.println("The array size is :"+array.getSize() + " and the array capacity is :"+array.getCapacity());
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array.printElements();
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}
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}
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