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dequeImp.java
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148 lines (136 loc) · 3.47 KB
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import java.util.* ;
import java.io.*;
public class Deque
{
// Initialize your data structure.
int[] dq;
int front, rear;
int size;
public Deque(int n)
{
// Write your code here.
size = n;
dq = new int[size];
front = rear = -1;
}
// Pushes 'X' in the front of the deque. Returns true if it gets pushed into the deque, and false otherwise.
public boolean pushFront(int x)
{
// Write your code here.
if(isFull()){
// deque is full
return false;
}
if(isEmpty()==true){
// when deque is empty
front=rear=0;
} else {
// deque is not empty
if(front==0){
front = size-1;
}else{
--front;
}
}
// insert the element at the front of deQue
dq[front] = x;
return true;
}
// Pushes 'X' in the back of the deque. Returns true if it gets pushed into the deque, and false otherwise.
public boolean pushRear(int x)
{
// Write your code here.
if(isFull()){
// deque is full
return false;
}
if(isEmpty()){
front = rear = 0;
}else{
if(rear==size-1){
rear = 0;
}else{
rear = rear + 1;
}
}
// Insert the element at the end of deque.
dq[rear] = x;
return true;
}
// Pops an element from the front of the deque. Returns -1 if the deque is empty, otherwise returns the popped element.
public int popFront()
{
// Write your code here.
if(isEmpty()){
return -1;
}
int item = dq[front];
if(front==rear){
front = rear = -1;
}else {
if(front == size-1){
front = 0;
} else{
front = front + 1;
}
}
return item;
}
// Pops an element from the back of the deque. Returns -1 if the deque is empty, otherwise returns the popped element.
public int popRear()
{
// Write your code here.
if(isEmpty()){
return -1;
}
int item = dq[rear];
if(front==rear){
front = rear = -1;
}else {
if(rear == 0){
rear = size-1;
} else{
rear = rear - 1;
}
}
return item;
}
// Returns the first element of the deque. If the deque is empty, it returns -1.
public int getFront()
{
// Write your code here.
if(isEmpty()){
return -1;
}
return dq[front];
}
// Returns the last element of the deque. If the deque is empty, it returns -1.
public int getRear()
{
// Write your code here.
if(isEmpty()){
return -1;
}
return dq[rear];
}
// Returns true if the deque is empty. Otherwise returns false.
public boolean isEmpty()
{
// Write your code here.
if (front == -1)
{
return true;
}
return false;
}
// Returns true if the deque is full. Otherwise returns false.
public boolean isFull()
{
// Write your code here.
if ((front == 0 && rear == size - 1) || (front == rear + 1))
{
return true;
}
return false;
}
}