Package g1201_1300.s1286_iterator_for_combination

Class CombinationIterator

java.lang.Object

g1201_1300.s1286_iterator_for_combination.CombinationIterator

public class CombinationIterator
extends Object

1286 - Iterator for Combination.<p>Medium</p> <p>Design the <code>CombinationIterator</code> class:</p> <ul> <li><code>CombinationIterator(string characters, int combinationLength)</code> Initializes the object with a string <code>characters</code> of <strong>sorted distinct</strong> lowercase English letters and a number <code>combinationLength</code> as arguments.</li> <li><code>next()</code> Returns the next combination of length <code>combinationLength</code> in <strong>lexicographical order</strong>.</li> <li><code>hasNext()</code> Returns <code>true</code> if and only if there exists a next combination.</li> </ul> <p><strong>Example 1:</strong></p> <p><strong>Input</strong> [&ldquo;CombinationIterator&rdquo;, &ldquo;next&rdquo;, &ldquo;hasNext&rdquo;, &ldquo;next&rdquo;, &ldquo;hasNext&rdquo;, &ldquo;next&rdquo;, &ldquo;hasNext&rdquo;] [[&ldquo;abc&rdquo;, 2], [], [], [], [], [], []]</p> <p><strong>Output:</strong> [null, &ldquo;ab&rdquo;, true, &ldquo;ac&rdquo;, true, &ldquo;bc&rdquo;, false]</p> <p><strong>Explanation:</strong> CombinationIterator itr = new CombinationIterator(&ldquo;abc&rdquo;, 2); itr.next(); // return &ldquo;ab&rdquo; itr.hasNext(); // return True itr.next(); // return &ldquo;ac&rdquo; itr.hasNext(); // return True itr.next(); // return &ldquo;bc&rdquo; itr.hasNext(); // return False</p> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= combinationLength <= characters.length <= 15</code></li> <li>All the characters of <code>characters</code> are <strong>unique</strong>.</li> <li>At most <code>10⁴</code> calls will be made to <code>next</code> and <code>hasNext</code>.</li> <li>It is guaranteed that all calls of the function <code>next</code> are valid.</li> </ul>

Constructor Summary

Constructors

Constructor	Description
CombinationIterator(String characters, int combinationLength)

Method Summary

Modifier and Type	Method	Description
boolean	hasNext()
String	next()

Methods inherited from class java.lang.Object

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

Constructor Details

CombinationIterator

public CombinationIterator(String characters,
 int combinationLength)

Method Details

next

public String next()

hasNext

public boolean hasNext()