剑指Offer --> Questions 35

<span style="font-family:Courier New;font-size:12px;">#include <iostream>#include <string>#include <iterator>using namespace std;const int CHARNUM = 256;unsigned char firstNotRepeatingChar(const string &s);int main(){string s;cin >> s;cout << firstNotRepeatingChar(s) << endl;}unsigned char firstNotRepeatingChar(const string &s){if (s.size() == 0){cout << "invalid input.";return '\0';}unsigned charCountInString[CHARNUM];for (auto &count : charCountInString){count = 0;}string temp = s;auto bIter = temp.begin();auto eIter = temp.end();while (bIter != eIter){charCountInString[static_cast<unsigned>(*bIter)]++;bIter++;}bIter = temp.begin();while (bIter != eIter && charCountInString[*bIter] != 1){bIter++;}if (bIter == eIter){cout << "Don't have a character appear only one.";return '\0';}else{return *bIter;}}</span>