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PancakeSort.java
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PancakeSort.java
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package Java.Sorting; /**
** @author Rahul Kumar
**
*/
import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;
import java.util.Arrays;
import java.util.Collections;
/*
Pancake sorting.....
Take n as number of elements in the array
Array : a[0,1....n-1]
Sort the array using pancake sort and print the sorted array elements
Sample I/O
input :
6
6 5 4 3 2 1
Output:
1 2 3 4 5 6 */
public class PancakeSort {
public static void flip(int arr[] , int i){
for(int j = 0 ; j <= (i / 2) ; j++)
{
int temp1 = arr[i-j] ;
arr[i-j] = arr[j] ;
arr[j] = temp1 ;
}
}
// time complexity = O(n) ; Space complexity = O(1)
public static int max_element(int arr[] , int n){
int maks = arr[0] ;
int temp = 0 ;
for(int i = 1 ; i < n ; i++)
{
if(maks < arr[i])
{
maks = arr[i] ;
temp = i ;
}
}
return temp ;
}
public static void pancake_sort(int arr[], int n) {
int curr_size=n ;
while(curr_size > 0){
int max_index = max_element(arr , curr_size) ;// time complexity = O(n) ; space complexity = O(1);
if(max_index !=curr_size -1)
{
flip(arr, max_index);
flip(arr, curr_size -1) ;
}
curr_size-- ;
}
}
//time complexity = O(n * max(p, q)) where p is the time complexity of flip() and q is the complexity of max_element(); space complexity = O(1)
public static void main(String[] args) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
int n = Integer.parseInt(br.readLine()); //reading n
int[] arr = new int[n];
String[] arrItems =br.readLine().split(" ");
for (int i = 0; i < n; i++) {
int arrItem = Integer.parseInt(arrItems[i]);
arr[i] = arrItem;
}
pancake_sort(arr,n);
for (int i=0;i<n;i++){
System.out.print(arr[i]+" ");
}
}
}//Overall time complexity = O(n) ; Overall Space complexity = O(1)