AreAnagrams.java

/*
 * Copyright (C) 2014 Pedro Vicente Gómez Sánchez.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.github.pedrovgs.problem29;

import java.util.Arrays;

/**
 * Given two Strings passed as parameter, can you write a method to return true if this words are
 * anagrams?
 *
 * For example:
 *
 * Input: ana,naa Output: true
 * Input: pedro,ana Output: false
 *
 * @author Pedro Vicente Gómez Sánchez.
 */
public class AreAnagrams {

  /**
   * Iterative algorithm to solve this problem. Two words are anagrams just if contains the same
   * number of letters. Using this property, we are going to sort and compare the letters inside
   * the array.  The complexity order of this algorithm is O(N*Log(N)) where N is the number of
   * letters in the largest word. In space terms, the complexity order of this algorithm is O(N).
   */
  public boolean check(String a, String b) {
    if (a == null || b == null) {
      throw new IllegalArgumentException("You can't use null Strings as input.");
    }
    if (a.length() != b.length()) {
      return false;
    }
    char[] charsA = a.toCharArray();
    Arrays.sort(charsA);
    char[] charsB = b.toCharArray();
    Arrays.sort(charsB);
    return Arrays.equals(charsA, charsB);
  }


}