Interesting !!!

CIRCULAR ARRAY ROTATION - (RIGHT)

ref : https://www.hackerrank.com/challenges/circular-array-rotation

Approach :  We have no need to do any shifts here,just an index arithmetic is enough i.e., 

for (int i = 0; i < n; i++) {

scanf("%d",&a[(i+k)%n]);   }

while reading the values itself !!!!

ARRAY LEFT ROTATION

ref : https://www.hackerrank.com/challenges/array-left-rotation/problem

Approach :  Same here, just an index arithmetic and it can be done in 2 ways :

1.with additional array : 

 for(int i=0;i<n;i++){

scanf("%d",&a[i]);

b[(n-d+i)%n] = a[i];

}

2.with no additional array : (cool :p)

where d = # of left rotations

 int l = n-d;

 for(int i=0;i<n;i++){

if(l == n)  

l = 0;

scanf("%d",&a[l++]);}

********************************BOMB OF THE DAY*******************************

ARRAY MANIPULATION

ref : https://www.hackerrank.com/challenges/crush/problem

Approach : If we follow naive approach or any most efficient sorting algorithm you will still get  TLE. So, I discovered something called a "prefix sum" (in the editorial of course :p)

Here, instead of updating m (queries) times, we update the l(add) and r+1(subtract) indices only and while finding the max. value in array, we keep on adding the values in the array [?]till we encounter 

-ve value[?] 

NAIVE - FAILED - TLE

for(long a0 = 0; a0 < m; a0++){

long a,b,k;

scanf("%ld %ld %ld", &a, &b, &k);

a--;

b--;

for(int i=a;i<=b;i++)

ar[i] = ar[i] + k;}

//used even merge sort

//still failed

WORKING - (PREFIX  SUM)

editorial link : https://www.hackerrank.com/challenges/crush/editorial  (but still didn't understood :p) 

for(i=0;i<k;i++){

long long int l,r,k;

scanf("%lld %lld %lld",&l,&r,&k);

a[l] = a[l] + k;

if(r+1<=n){

a[r+1] = a[r+1] - k;}

}

for(i=1;i<=n;i++){

x = x + a[i];

if(max<x){

max=x;   }

}

printf("%lld",max);

That's it !!!!! Need to get my head around it.