2013.12.15 22:00
Given an array of strings, return all groups of strings that are anagrams.
Note: All inputs will be in lower-case.
Solution:
Anagrams means that strings composed of the same group of letters, such as [ate, eat, tea]. They'll become the same when sorted: aet.
My solution is to sort every string, and sort the array according to the sorted form of each string element. Then group the strings together by anagrams.
Time compexity is O(n * log(n)), where n is the length of the array. Space complexity is O(n).
Accepted code:
1 // 1CE, 1AC 2 #include <algorithm> 3 #include <cstring> 4 #include <string> 5 using namespace std; 6 7 typedef struct st{ 8 public: 9 string str; 10 string sorted_str; 11 12 st(string _str = "", string _sorted_str = "") { 13 str = _str; 14 sorted_str = _sorted_str; 15 } 16 }st; 17 18 bool comparator(const st &x, const st &y) 19 { 20 // 1CE here, return a.sorted_str < b.sorted_str; 21 return x.sorted_str < y.sorted_str; 22 } 23 24 class Solution { 25 public: 26 vector<string> anagrams(vector<string> &strs) { 27 // IMPORTANT: Please reset any member data you declared, as 28 // the same Solution instance will be reused for each test case. 29 int max_len = 0; 30 int i, j, n; 31 char *ps = nullptr; 32 33 result.clear(); 34 v.clear(); 35 36 n = strs.size(); 37 if(n <= 0){ 38 return result; 39 } 40 for(i = 0; i < n; ++i){ 41 if(strs[i].length() > max_len){ 42 max_len = strs[i].length(); 43 } 44 } 45 ps = new char[max_len + 1]; 46 47 string s, ss; 48 for(i = 0; i < n; ++i){ 49 s = strs[i]; 50 strcpy(ps, s.data()); 51 sort(ps, ps + s.length()); 52 ss = string(ps); 53 v.push_back(st(s, ss)); 54 } 55 sort(v.begin(), v.end(), comparator); 56 delete[] ps; 57 i = 0; 58 while(i < n){ 59 j = i; 60 while(j < n && v[i].sorted_str == v[j].sorted_str){ 61 ++j; 62 } 63 if(j - i > 1){ 64 while(i < j){ 65 result.push_back(v[i].str); 66 ++i; 67 } 68 } 69 i = j; 70 } 71 v.clear(); 72 73 return result; 74 } 75 private: 76 vector<st> v; 77 vector<string> result; 78 };
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