leetcode/java/242_Valid_Anagram.java at master · cphysics/leetcode

Repository navigation

https://leetcode.com/problems/valid-anagram/

Given two strings s and t, write a function to determine if t is an anagram of s.

In an array count the frequency of each char in the first string. For each char in the second string decrement

the count. At least one char count must be negative if the strings are not anagrams.

Time - O(n)

Space - O(1)

public class Solution {

public boolean isAnagram(String s, String t) {

if (s.length() != t.length()) // early return

return false;

int[] letterCounts = new int[26];

for (int i = 0; i < s.length(); ++i) {

char c = s.charAt(i);

letterCounts[(int) c - (int) 'a']++;

}

for (int i = 0; i < t.length(); ++i) {

char c = t.charAt(i);

letterCounts[(int) c - (int) 'a']--;

if (letterCounts[(int) c - (int) 'a'] < 0)

return false;

}

return true;

}