Valid Anagram | DSA Journal

Question

Given two strings, check if one is an anagram of the other. An anagram means both strings contain the same characters, just in a different order.

You must return true if they are anagrams, false otherwise.

Example

Input: "listen", "silent"

Output: true

Explanation: Both strings use the same letters.

Input: "rat", "car"

Output: false

Explanation: The characters don't match.

Input: "a", "a"

Output: true

Explanation: Same one-character string.

My Notes

Compare string lengths first — quick fail if different.
Use a hash map to count characters in the first string.
Then subtract counts using the second string.
If any character is missing or goes below zero, return false.
If the map is empty at the end, the strings are valid anagrams.

package main

import (
    "fmt"
)

func main() {
    result := isAnagram("anagram", "nagaram")
    fmt.Println(result)
}

func isAnagram(s string, t string) bool {
    lookup := make(map[rune]int)

    if len(s) != len(t) {
        return false
    }

    for _, ch := range s {
        lookup[ch]++
    }

    for _, ch := range t {
        if _, ok := lookup[ch]; !ok {
            return false
        }
        lookup[ch]--
        if lookup[ch] == 0 {
            delete(lookup, ch)
        }
    }

    return true
}