README_EN.md

10.02. Group Anagrams

中文文档

Description

Write a method to sort an array of strings so that all the anagrams are in the same group.

Note: This problem is slightly different from the original one the book.

Example:

Input: ["eat", "tea", "tan", "ate", "nat", "bat"],

Output:

[

  ["ate","eat","tea"],

  ["nat","tan"],

  ["bat"]

]

Notes:

• All inputs will be in lowercase.
• The order of your output does not matter.

Solutions

key	value
"aet"	["eat", "tea", "ate"]
"ant"	["tan", "nat"]
"abt"	["bat"]

Python3

class Solution:
    def groupAnagrams(self, strs: List[str]) -> List[List[str]]:
        chars = defaultdict(list)
        for s in strs:
            k = ''.join(sorted(list(s)))
            chars[k].append(s)
        return list(chars.values())

Java

class Solution {
    public List<List<String>> groupAnagrams(String[] strs) {
        Map<String, List<String>> chars = new HashMap<>();
        for (String s : strs) {
            char[] t = s.toCharArray();
            Arrays.sort(t);
            String k = new String(t);
            chars.computeIfAbsent(k, key -> new ArrayList<>()).add(s);
        }
        return new ArrayList<>(chars.values());
    }
}

C++

class Solution {
public:
    vector<vector<string>> groupAnagrams(vector<string> &strs) {
        unordered_map<string, vector<string>> chars;
        for (auto s : strs)
        {
            string k = s;
            sort(k.begin(), k.end());
            chars[k].emplace_back(s);
        }
        vector<vector<string>> res;
        for (auto it = chars.begin(); it != chars.end(); ++it)
        {
            res.emplace_back(it->second);
        }
        return res;
    }
};

Go

func groupAnagrams(strs []string) [][]string {
	chars := map[string][]string{}
	for _, s := range strs {
		key := []byte(s)
		sort.Slice(key, func(i, j int) bool {
			return key[i] < key[j]
		})
		chars[string(key)] = append(chars[string(key)], s)
	}
	var res [][]string
	for _, v := range chars {
		res = append(res, v)
	}
	return res
}

TypeScript

function groupAnagrams(strs: string[]): string[][] {
    const map = new Map<string, string[]>();
    for (const s of strs) {
        const k = s.split('').sort().join();
        map.set(k, (map.get(k) || []).concat([s]));
    }
    return [...map.values()];
}

Rust

use std::collections::HashMap;

impl Solution {
    pub fn group_anagrams(strs: Vec<String>) -> Vec<Vec<String>> {
        let mut map = HashMap::new();
        for s in strs {
            let key = {
                let mut cs = s.chars().collect::<Vec<char>>();
                cs.sort();
                cs.iter().collect::<String>()
            };
            map.entry(key).or_insert(vec![]).push(s);
        }
        map.into_values().collect()
    }
}

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