0242 - Valid Anagram (Easy)

Problem Link

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

Problem Statement

Given two strings s and t, return true if t is an anagram of s, and false otherwise.

An Anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once.

Example 1:

Input: s = "anagram", t = "nagaram"
Output: true

Example 2:

Input: s = "rat", t = "car"
Output: false

Constraints:

• 1 <= s.length, t.length <= 5 * 10^4
• s and t consist of lowercase English letters.

Follow up: What if the inputs contain Unicode characters? How would you adapt your solution to such a case?

Approach 1: Sort

C++

Written by @wingkwong

class Solution {
public:
    bool isAnagram(string s, string t) {
        // s and t are anagrams
        // if they are same after being sorted
        sort(begin(s), end(s));
        sort(begin(t), end(t));
        return s == t;
    }
};

Java

Written by @vigneshshiv

class Solution {
    public boolean isAnagram(String s, String t) {
        char[] s_chars = s.toCharArray();
        char[] t_chars = t.toCharArray();
        // Sorting with char array
        Arrays.sort(s_chars);
        Arrays.sort(t_chars);
        // Convert to string
        s = new String(s_chars);
        t = new String(t_chars);
        return s.equals(t);
    }
}

Python

Written by @radojicic23

class Solution:
    def isAnagram(self, s: str, t: str) -> bool:
        # if they are same after sorting they are anagrams
        return sorted(t) == sorted(s)

JavaScript

Written by @radojicic23

/**
 * @param {string} s
 * @param {string} t
 * @return {boolean}
 */
var isAnagram = function(s, t) {
    // sort strings 
    const sorted_s = s.split('').sort().join('');
    const sorted_t = t.split('').sort().join('');
    // if they are same after sorting they are anagrams
    return sorted_s == sorted_t;
};

Approach 2: Counting

C++

Written by @wingkwong

class Solution {
public:
    bool isAnagram(string s, string t) {
        // if s and t are anagram, 
        // then the frequency of each character would be same
        int cnt[26] = {0};
        for (auto x : s) cnt[x - 'a']++;
        for (auto x : t) cnt[x - 'a']--;
        for (int i = 0; i < 26; i++) {
            if (cnt[i]) {
                return false;
            }
        }
        return true;
    }
};

Java

Written by @vigneshshiv

class Solution {
    public boolean isAnagram(String s, String t) {
        int[] chars = new int[26];
        for (char c : s.toCharArray()) {
            chars[c - 'a']++;
        }
        for (char c : t.toCharArray()) {
            chars[c - 'a']--;
            // If any char is occurred more than "s string" char, then immediately return false. 
            if (chars[c - 'a'] < 0) return false;
        }
        for (int num : chars) {
            if (num != 0) return false;
        }
        return true;
    }
}

Go

Written by @wingkwong

// if s and t are anagram, 
// then the frequency of each character would be same
func isAnagram(s string, t string) bool {
    cnt := [26]int{}
	for _, x := range s { cnt[x -'a']++ }
    for _, x := range t { cnt[x -'a']-- }
	for _, c := range cnt {
		if c != 0 {
			return false
		}
	}
	return true
}

Rust

Written by @jit

impl Solution {
    // Frequency counting:
    pub fn is_anagram(s: String, t: String) -> bool {
        let mut cnts = [0; u8::MAX as usize];
        for a in s.bytes() { cnts[a as usize] += 1; }
        for b in t.bytes() { cnts[b as usize] -= 1; }
        cnts.iter().all(|&ct| ct == 0)
    }
}