그룹 애너그램. (DSA 시리즈 2)

문제

해결책

/**
 * for each item in array, sort alphabetically, then add sorted item to map as key, push index to value array eg; {aet:[0,1,3], ...}
 * return values of every word(key) in the map as an array.
 * Time Complexity is O(n)... I think. _Not sure if the sorting of each word takes an additional O(n)_ 
 */
function groupAnagram(arr){
    const map = {}
    for(let i = 0; i < arr.length; i++) {
       const sortedWord = [...arr[i] ].sort((a,b)=> a.localeCompare(b)).join();
       map[sortedWord] = map[sortedWord] !== undefined ? [...map[sortedWord], arr[i]] : [arr[i]]
    }

    return Object.values(map);
}