Given an array of strings, 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, using all the original letters exactly once.
Example:
Input: strings = ["eat","tea","tan","ate","nat","bat"] Output: [["bat"],["nat","tan"],["ate","eat","tea"]]
For this lesson, your algorithm should run in O(n * log n * L * log L) time and use O(n * L) extra space.
(There are faster solutions which we will discuss in future lessons)
The core challenge of this problem is to identify and group words that are anagrams of each other. An anagram is a rearrangement of the letters of a word to form another word. For example, "eat" and "tea" are anagrams because they contain the same letters.
This problem is significant in various applications such as text analysis, cryptography, and natural language processing where identifying similar patterns is crucial.
Potential pitfalls include not handling different cases (e.g., uppercase vs lowercase) and not efficiently grouping the anagrams.
To solve this problem, we need to identify a way to group words that are anagrams. A naive solution might involve comparing each word with every other word, but this would be inefficient.
A more optimized approach involves sorting the characters of each word. Anagrams, when sorted, will result in the same string. For example, "eat" and "tea" both become "aet" when sorted. We can use this property to group anagrams together.
The naive solution involves comparing each word with every other word to check if they are anagrams. This approach is not optimal due to its high time complexity.
We can use a hash map to group words by their sorted character strings. The key will be the sorted string, and the value will be a list of words that match this sorted string.
1. Initialize an empty hash map.
2. Iterate through each word in the input array.
3. Sort the characters of the word to form the key.
4. If the key is not in the hash map, add it with an empty list as its value.
5. Append the original word to the list corresponding to the key.
6. Return the values of the hash map as the grouped anagrams.
// Function to group anagrams
function groupAnagrams(strs) {
// Initialize a hash map to store grouped anagrams
const map = new Map();
// Iterate through each word in the input array
for (let str of strs) {
// Sort the characters of the word to form the key
const sortedStr = str.split('').sort().join('');
// If the key is not in the hash map, add it with an empty list as its value
if (!map.has(sortedStr)) {
map.set(sortedStr, []);
}
// Append the original word to the list corresponding to the key
map.get(sortedStr).push(str);
}
// Return the values of the hash map as the grouped anagrams
return Array.from(map.values());
}
// Example usage
const strings = ["eat", "tea", "tan", "ate", "nat", "bat"];
console.log(groupAnagrams(strings));
The time complexity of this solution is O(n * log n * L * log L), where n is the number of words and L is the maximum length of a word. This is because sorting each word takes O(L * log L) time, and we do this for each of the n words.
The space complexity is O(n * L) because we store each word in the hash map.
Potential edge cases include:
To test the solution comprehensively, consider the following test cases:
When approaching such problems, it's essential to:
Grouping anagrams is a common problem that can be efficiently solved using hash maps and sorting. Understanding the properties of anagrams and leveraging data structures like hash maps can lead to optimal solutions.
Practice and exploration of similar problems can help improve problem-solving skills and algorithmic thinking.
Our interactive tutorials and AI-assisted learning will help you master problem-solving skills and teach you the algorithms to know for coding interviews.
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