How to change arrangement of element using pointer in c

Question

Here is my code, how can I change line 9 to line 11 in pointer form?

void ShiftRightCircular (ElemType *A, int n, int k) {
    /************** begin *****************/
    ElemType e;
    int p, i = 0;
    while (i < n - k) {
        p = i / k + 1;
        for (int j = 0; j < k ; j++) {
            e = A[j];                // line 9
            A[j] = A[ (p * k + j) % n]; // line 10
            A[ (p * k + j) % n] = e; // line 11
            i++;
        }
    }
    /************** end *****************/
}

Answer 1

array[index] is 100% equivalent to *(array + index)

Candidate replacement:

int d = (p * k + j) % n;  // Used to simplify the following:

e = *(A + j);        // e = A[j];
*(A + j) = *(A + d); // A[j] = A[ (p * k + j) % n];
*(A + d) = e;        // A[ (p * k + j) % n] = e;

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Note: (p * k + j) % n better as (1LL * p * k + j) % n to avoid overflow.