字符流中第一个只出现一次的字符－C++

分享一个大牛的人工智能教程。零基础通俗易懂风趣幽默希望你也加入到人工智能的队伍中来请轻击人工智能教程​​​​​​https://www.captainai.net/troubleshooter// 面试题50二字符流中第一个只出现一次的字符 // 题目请实现一个函数用来找出字符流中第一个只出现一次的字符。例如当从 // 字符流中只读出前两个字符go时第一个只出现一次的字符是g。当从该字 // 符流中读出前六个字符google时第一个只出现一次的字符是l。 #include cstdio #include vector #include limits using namespace std; class CharStatistics { public: CharStatistics() : index(0) { for (int i 0; i 256; i) occurrence[i] -1; } void Insert(char ch) { if (occurrence[ch] -1) occurrence[ch] index; else if (occurrence[ch] 0) occurrence[ch] -2; index; } char FirstAppearingOnce() { char ch \0; int minIndex numeric_limitsint::max(); for (int i 0; i 256; i) { if (occurrence[i] 0 occurrence[i] minIndex) { ch (char)i; minIndex occurrence[i]; } } return ch; } private: // occurrence[i]: A character with ASCII value i; // occurrence[i] -1: The character has not found; // occurrence[i] -2: The character has been found for mutlple times // occurrence[i] 0: The character has been found only once int occurrence[256]; int index; }; // 测试代码 void Test(const char *testName, CharStatistics chars, char expected) { if (testName ! nullptr) printf(%s begins: , testName); if (chars.FirstAppearingOnce() expected) printf(Passed.\n); else printf(FAILED.\n); } int main(int argc, char *argv[]) { CharStatistics chars; Test(Test1, chars, \0); chars.Insert(g); Test(Test2, chars, g); chars.Insert(o); Test(Test3, chars, g); chars.Insert(o); Test(Test4, chars, g); chars.Insert(g); Test(Test5, chars, \0); chars.Insert(l); Test(Test6, chars, l); chars.Insert(e); Test(Test7, chars, l); return 0; } // ------ Output ------ /* Test1 begins: Passed. Test2 begins: Passed. Test3 begins: Passed. Test4 begins: Passed. Test5 begins: Passed. Test6 begins: Passed. Test7 begins: Passed. */