rotate, C++ (gcc) - rextester

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//g++  7.4.0

//write a function that rotates first n elements of array a , k positions to the right; the last k elements are rotated around to the beginning of array a;
//this code is created by Rezaul Hoque on June 16,2021; contact: jewelmrh@yahoo.com
//note: codes shared by Rezaul Hoque on rextester are not for sale; they are created and shared to facilitate the algorithm learning process; many like Hoque use this platform to practice programming ;Rezaul hopes his contribution helps others to fine tune their  learning;

#include <iostream>
using namespace std;
int n=8, k=2;

void rotate(int [], int, int);
void rotate(int a[], int n, int k){
//first we have to create three buffer arrays, each having the same size of a; then they are initialized with 0s;
int b[n]={0,0,0,0,0,0,0,0};
int c[n]={0,0,0,0,0,0,0,0};
int d[n]={0,0,0,0,0,0,0,0};

for(int i=0;i<k;i++){//note loop continuing condition is smaller than k position
b[i]=a[n-k+i];//array b holds the elements of array a,starting from index n-k+i;if i=0 & k=2, a[6]; when i=1,a[7];so b now looks like b[n]={16,17,0,0,0,0,0,0};

a[n-k+i]=0;//having copied the elements staring from index k, fill them with 0; so a[n]={10,11,12,13,14,15,0,0};
}
for(int i=0;i<n-k;i++){
c[i+k]=a[i];//copy the elements of a to array c at the index starting from k; so c[n]={0,0,10,11,12,13,14,15};

}
for(int i=0;i<n;i++){
d[i]=b[i]+c[i];//finally the resultant array d holds the sum of the elements of  b and c;so d [n]={16,17,10,11,12,13,14,15};

}

for(int i=0;i<n;i++){
cout<<" "<<d[i];
  }
}

int main()
{
int a[n]={10,11,12,13,14,15,16,17};
rotate(a,8,2);
return 0;
}

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Compilation time: 0.42 sec, absolute running time: 0.15 sec, cpu time: 0.01 sec, memory peak: 5 Mb, absolute service time: 0,61 sec