C / C++ / MFC

Quote:

Input : arr[] : {1, 2, 3, 4, 5}
ranges[] = { {0, 2}, {0, 3} }
index : 1
Output : 3
Explanation : After first given rotation {0, 2}
arr[] = {3, 1, 2, 4, 5}
After second rotation {0, 3}
arr[] = {4, 3, 1, 2, 5}
After all rotations we have element 3 at given
index 1.

// CPP code to rotate an array
// and answer the index query
#include <bits/stdc++.h>
using namespace std;

// Function to compute the element at
// given index
int findElement(int arr[], int ranges[][2],
               int rotations, int index)
{
    for (int i = rotations - 1; i >= 0; i--) {

        // Range[left...right]
        int left = ranges[i][0];
        int right = ranges[i][1];

        // Rotation will not have any effect
        if (left <= index && right >= index) {
            if (index == left)
                index = right;
            else
                index--;
        }
    }

    // Returning new element
    return arr[index];
}

// Driver
int main()
{
    int arr[] = { 1, 2, 3, 4, 5 };

    // No. of rotations
    int rotations = 2;

    // Ranges according to 0-based indexing
    int ranges[rotations][2] = { { 0, 2 }, { 0, 3 } };

    int index = 1;

    cout << findElement(arr, ranges, rotations, index);

    return 0;

}

Quote:

and the authors logic: