第二题应该是这样写才对吧 string miniNum(string s) { vector<int> dp(10, 0); for (int i = 0; i < s.size(); i++) { dp[s[i] - '0']++; } int index = min_element(dp.begin() + 1, dp.end()) - dp.begin(); return (*dp.begin() + 1 <= dp[index]) ? ("1" + string(dp[0] + 1, '0')) : (string(dp[index] + 1, index + '0')); }