Vector之是否含有重复元素和乱序排列

vector<string> allAnswers;
	
	while(allAnswers.size()<3){
		int answer_i = rand()%RANGE;
		char answer_str[ARRAYSIZE]={0};
		sprintf(answer_str,"%d",answer_i);
		vector<string>::iterator result = find( allAnswers.begin( ), allAnswers.end( ), answer_str);
		if(result == allAnswers.end( ) && answer_str!=answer){
			allAnswers.push_back(answer_str);
		}
	}
		allAnswers.push_back(answer);
		random_shuffle (allAnswers.begin(), allAnswers.end());