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49. Group Anagrams

Medium

Given an array of strings strs, group the anagrams together. You can return the answer in any order.

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: strs = [“eat”,”tea”,”tan”,”ate”,”nat”,”bat”]

Output: [[“bat”],[“nat”,”tan”],[“ate”,”eat”,”tea”]]

Example 2:

Input: strs = [””]

Output: [[””]]

Example 3:

Input: strs = [“a”]

Output: [[“a”]]

Constraints:

• 1 <= strs.length <= 104
• 0 <= strs[i].length <= 100
• strs[i] consists of lowercase English letters.

Solution

function groupAnagrams(strs: string[]): string[][] {
    if (strs.length === 1) return [strs]
    const map = new Map()
    function getKey(str: string): string {
        const charCount = Array(26).fill(0)
        for (const char of str) {
            charCount[char.charCodeAt(0) - 'a'.charCodeAt(0)]++
        }
        return charCount.join('#')
    }
    for (const str of strs) {
        const key = getKey(str)
        if (map.has(key)) {
            map.get(key).push(str)
        } else {
            map.set(key, [str])
        }
    }
    return Array.from(map.values())
}

export { groupAnagrams }

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