Problem:
Merge Sort

Write a program of a Merge Sort algorithm implemented by the following pseudocode. You should also report the number of comparisons in the Merge function.

Merge(A, left, mid, right)
n1 = mid - left;
n2 = right - mid;
create array L[0...n1], R[0...n2]
for i = 0 to n1-1
do L[i] = A[left + i]
for i = 0 to n2-1
do R[i] = A[mid + i]
L[n1] = SENTINEL
R[n2] = SENTINEL
i = 0;
j = 0;
for k = left to right-1
if L[i] <= R[j]
then A[k] = L[i]
i = i + 1
else A[k] = R[j]
j = j + 1

Merge-Sort(A, left, right){
if left+1 < right
then mid = (left + right)/2;
call Merge-Sort(A, left, mid)
call Merge-Sort(A, mid, right)
call Merge(A, left, mid, right)

Input

In the first line n is given. In the second line, n integers are given.

Output

In the first line, print the sequence S. Two consequtive elements should be separated by a space character.

In the second line, print the number of comparisons.

Constraints

n ≤ 500000

0 ≤ an element in S ≤ 109

Sample Input 1

10
8 5 9 2 6 3 7 1 10 4

Sample Output 1

1 2 3 4 5 6 7 8 9 10
34

Notes

Solution in C (judge verdict: Accepted)

#include <stdio.h>

#define INFTY 1000000000

void merge(int *,int ,int ,int);
void mergeSort(int *,int,int);

int S[500000],L[500000],R[500000];
int count;

int main(){
  
  int n,i;

  scanf("%d",&n);
  for(i=0;i<n;i++){
    scanf("%d",&S[i]);
  }

  mergeSort(S,0,n);

  for(i=0;i<n;i++){
    printf("%d",S[i]);
    if(i<n-1) printf(" ");
  }
  printf("\n");
  printf("%d\n",count);
    
  
  return 0;

}

void merge(int A[],int left,int mid,int right){

  int n1,n2,i,k,j;
  
  n1 = mid - left;
  n2 = right - mid;
  for(i = 0 ;i<= n1-1;i++){
    L[i] = A[left + i];
  }
  for(i = 0; i<= n2-1;i++){
    R[i] = A[mid + i];
  }
  L[n1] = INFTY;
  R[n2] = INFTY;
  i = 0;
  j = 0;
  for (k = left; k< right;k++){
    if (L[i] <= R[j]){
      A[k] = L[i];
      i = i + 1;
    }
    else{ 
      A[k] = R[j];
      j = j + 1;
    }
    count++;
  }
}

void mergeSort(int A[],int left,int right){
  if(left+1<right){
    int mid;
    mid=(left+right)/2;
    mergeSort(A, left, mid);
    mergeSort(A, mid, right);
    merge(A, left, mid, right);
  }
}