// B #include <string> #include <iostream> #include <map> #include <functional> using namespace std; //按key排序，greater()，从大到小 map<int, int, greater<int>> m; //存储符合要求的字符串区间，<size, 起始位置> string str; //存储输入的字符串 int count = 0; //输入的字符串的size是count void Skip_same_letters(int& flag, int& prev, char& prev_char, const int end_position) { int i = 0; for (i = end_position; i < str.size() && str[i] == prev_char; i++) ; prev = i - 3; prev_char = 0; flag = 0; } int main() { cin >> ::count; //输入的字符串的size是count cin >> str; if (::count < 3) //如果输入的字符小于三个，一定不符合要求，直接返回0 cout << 0; int flag = 0; //判断是否需要优化 int prev = 0, cur = 1, next = 2; //不会出现野指针的情况，小于三个的情况已经被特殊处理 int start_position = -1; //记录最开始的位置 int end_position = -1; //记录最后的位置 char prev_char = 0; //不能越界 while (next < str.size()) { start_position = prev; //开始记录 while (next < str.size() && str[prev] == str[cur] && str[prev] == str[next]) { prev += 3, cur += 3, next += 3; if (prev >= str.size()) break; prev_char = str[prev - 1]; if (str[prev] == prev_char) { flag = 1; //需要优化 break; } } end_position = prev; m.insert({ end_position - start_position, start_position }); //将当前符合要求的加入map prev = start_position + 1; //从起始位置的下一个开始，遍历所有可能 if (flag) Skip_same_letters(flag, prev, prev_char, end_position); cur = prev + 1, next = cur + 1; } if (next >= str.size()) { auto it = m.begin(); cout << it->first / 3; } return 0; }