Given a string S, we can transform every letter individually to be lowercase or uppercase to create another string. Return a list of all possible strings we could create.
Examples:
Input: S = "a1b2"
Output: ["a1b2", "a1B2", "A1b2", "A1B2"]
Input: S = "3z4"
Output: ["3z4", "3Z4"]
Input: S = "12345"
Output: ["12345"]
Note:
Swill be a string with length at most12.Swill consist only of letters or digits.
将S的每个字母进行大写小小写转换，求出所有的可能
C++（9ms）： BFS
1 class Solution { 2 public: 3 vector<string> letterCasePermutation(string S) { 4 queue<string> que ; 5 que.push(S) ; 6 for(int i = 0 ; i < S.size() ; i++){ 7 if (isdigit(S[i])) 8 continue ; 9 int len = que.size() ; 10 for (int j = 0 ; j < len ; j++){ 11 string cur = que.front() ; 12 que.pop() ; 13 14 cur[i] = toupper(cur[i]); 15 que.push(cur) ; 16 17 cur[i] = tolower(cur[i]) ; 18 que.push(cur) ; 19 } 20 } 21 vector<string> res ; 22 int len = que.size() ; 23 for(int i = 0 ; i < len ; i++){ 24 res.push_back(que.front()) ; 25 que.pop() ; 26 } 27 return res ; 28 } 29 };
