Package g0801_0900.s0900_rle_iterator

Class RLEIterator

  • public class RLEIterator
extends Object
    900 - RLE Iterator.

    Medium

    We can use run-length encoding (i.e., RLE ) to encode a sequence of integers. In a run-length encoded array of even length encoding ( 0-indexed ), for all even i, encoding[i] tells us the number of times that the non-negative integer value encoding[i + 1] is repeated in the sequence.

    • For example, the sequence arr = [8,8,8,5,5] can be encoded to be encoding = [3,8,2,5]. encoding = [3,8,0,9,2,5] and encoding = [2,8,1,8,2,5] are also valid RLE of arr.

    Given a run-length encoded array, design an iterator that iterates through it.

    Implement the RLEIterator class:

    • RLEIterator(int[] encoded) Initializes the object with the encoded array encoded.
    • int next(int n) Exhausts the next n elements and returns the last element exhausted in this way. If there is no element left to exhaust, return -1 instead.

    Example 1:

    Input

    [“RLEIterator”, “next”, “next”, “next”, “next”]

    [3, 8, 0, 9, 2, 5, [2], [1], [1], [2]]

    Output: [null, 8, 8, 5, -1]

    Explanation:

     RLEIterator rLEIterator = new RLEIterator([3, 8, 0, 9, 2, 5]); // This maps to the sequence [8,8,8,5,5].
 rLEIterator.next(2); // exhausts 2 terms of the sequence, returning 8. The remaining sequence is now [8, 5, 5].
 rLEIterator.next(1); // exhausts 1 term of the sequence, returning 8. The remaining sequence is now [5, 5].
 rLEIterator.next(1); // exhausts 1 term of the sequence, returning 5. The remaining sequence is now [5].
 rLEIterator.next(2); // exhausts 2 terms, returning -1. This is because the first term exhausted was 5,
 // but the second term did not exist. Since the last term exhausted does not exist, we return -1.

    Constraints:

    • 2 <= encoding.length <= 1000
    • encoding.length is even.
    • 0 <= encoding[i] <= 109
    • 1 <= n <= 109
    • At most 1000 calls will be made to next.

    • Constructor Detail

      • RLEIterator

        public RLEIterator​(int[] encoding)

    • Method Detail

      • next

        public int next​(int n)