[topcoder]HappyLetterDiv2
http://community.topcoder.com/stat?c=problem_statement&pm=13245
就是有字符串,里面的字符可以随意两两消除,如果不等的话,那么最后如果留下一个字符,这个字符就是winning letter。如果任意方法消除都是这个winning letter,叫做happy letter。求happy letter是否存在。题目其实就是找众数。要注意的是求完了还要扫一遍是不是大于length/2。
#include <string> using namespace std; class HappyLetterDiv2 { public: char getHappyLetter(string letters) { char ch = letters[0]; int count = 1; int n = letters.size(); for (int i = 1; i < n; i++) { if (count > 0 && letters[i] != ch) { count--; } else // count == 0 || letters[i] == ch { count++; ch = letters[i]; } } count = 0; for (int i = 0; i < n; i++) { if (letters[i] == ch) count++; } if (count > n / 2) return ch; else return '.'; } };