49.md

49. Group Anagrams

Given an array of strings, group anagrams together.

For example, given: ["eat", "tea", "tan", "ate", "nat", "bat"], 
Return:

[
  ["ate", "eat","tea"],
  ["nat","tan"],
  ["bat"]
]
Note: All inputs will be in lower-case.

my thoughts:

1. iterate the list. convert each word to a letter:count key, store all word with same key in dd. return values of dd.

my solution:

**********292 ms
class Solution:
    def groupAnagrams(self, strs):
        """
        :type strs: List[str]
        :rtype: List[List[str]]
        """
        dd = {}
        for st in strs:
            d = {}
            for c in st:
                d[c] = d.get(c, 0)+1
            t = []
            for k, v in sorted(d.items()):
                t.append(k+str(v))
            key = ''.join(t)
            if key in dd:
                dd[key].append(st)
            else:
                dd[key] = [st]
            
        return list(dd.values())

my comments:

from other ppl's solution:

1. move efficient way to generator key, 199ms:
class Solution:
    def groupAnagrams(self, strs):
        """
        :type strs: List[str]
        :rtype: List[List[str]]
        """
        
        solution = {}
        
        
        for string in strs:
            
                
            key = "".join(sorted(string))
            if key in solution:
                solution[key].append(string)
            else:
                solution[key] = [string]
                
        return list(solution.values())