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| class Solution {
public:
vector<string> letterCasePermutation(string S) {
vector<string> wjl;
permutation(wjl, S, 0);
return wjl;
}
private:
void permutation(vector<string>& wjl, string s, int index) {
wjl.push_back(s);
if(index >= s.size()) return;
for(int i = index; i < s.size(); i++) {
if (isalpha(s[i])) {
s[i] ^= 32;
permutation(wjl, s, i + 1);
s[i] ^= 32;
}
}
}
};
|