[LintCode] Two Strings Are Anagrams

Write a method anagram(s,t) to decide if two strings are anagrams or not.

Clarification

What is Anagram?
- Two strings are anagram if they can be the same after change the order of characters.

Example

Given s = "abcd", t = "dcab", return true.
Given s = "ab", t = "ab", return true.
Given s = "ab", t = "ac", return false.

Challenge 

O(n) time, O(1) extra space

 

Solution: 

This problem is very simple with hash maps. Store all characters and their frequencies from s, then check if t has exactly the same character set with 

the same frequencies for each character.

 

 1 public class Solution {
 2     public boolean anagram(String s, String t) {
 3         if(s == null || t == null || s.length() != s.length()){
 4             return false;
 5         }
 6         int[] chars = new int[256];
 7         for(int i = 0; i < s.length(); i++){
 8             chars[s.charAt(i)]++;
 9         }
10         for(int i = 0; i < t.length(); i++){
11             if(chars[t.charAt(i)] == 0){
12                 return false;
13             }
14             else{
15                 chars[t.charAt(i)]--;
16             }
17         }
18         return true;
19     }
20 }

 

 

posted @ 2017-06-06 00:29  Review->Improve  阅读(220)  评论(0编辑  收藏  举报