Package g1201_1300.s1286_iterator_for_combination

Class CombinationIterator

  • All Implemented Interfaces:
    
public final class CombinationIterator

    1286 - Iterator for Combination\.

    Medium

    Design the CombinationIterator class:

    • CombinationIterator(string characters, int combinationLength) Initializes the object with a string characters of sorted distinct lowercase English letters and a number combinationLength as arguments.

    • next() Returns the next combination of length combinationLength in lexicographical order.

    • hasNext() Returns true if and only if there exists a next combination.

    Example 1:

    Input "CombinationIterator", "next", "hasNext", "next", "hasNext", "next", "hasNext" ["abc", 2, [], [], [], [], [], []]

    Output: null, "ab", true, "ac", true, "bc", false

    Explanation: CombinationIterator itr = new CombinationIterator("abc", 2); itr.next(); // return "ab" itr.hasNext(); // return True itr.next(); // return "ac" itr.hasNext(); // return True itr.next(); // return "bc" itr.hasNext(); // return False

    Constraints:

    • 1 <= combinationLength <= characters.length <= 15

    • All the characters of characters are unique.

    • At most <code>10<sup>4</sup></code> calls will be made to next and hasNext.

    • It is guaranteed that all calls of the function next are valid.

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description

    • Field Summary

      Fields 
      Modifier and Type Field Description

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description

    • Method Summary

      Modifier and Type Method Description
      final String next()
      final Boolean hasNext()

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait