可以在不想做选择题的时候蒙一些选项，支持单选和不定项选择。

#include<bits/stdc++.h>
using namespace std;
int type,a;
int main(){
srand(time(NULL));
	cout<<"0:单选"<<endl<<"1:不定项选择"<<endl;
	scanf("%d",&type);
	cout<<"题目个数"<<endl;
	scanf("%d",&a);
	switch(type){
		case 0:
			for(int i=1;i<=a;++i){
				int n=rand()%4+1;
				switch(n){
					case 1:printf("A ");break;
					case 2:printf("B ");break;
					case 3:printf("C ");break;
					case 4:printf("D ");break;
				}
			}
			break; 
		case 1:
			for(int i=1;i<=a;++i){
				int num[10]={0};
				bool done[5]={false,false,false,false,false};
				int p=rand()%4+1;
				for(int j=1;j<=p;++j){
					int n=rand()%4+1;
					bool flag=false;
					num[j]=n;
				}
				sort(num+1,num+p+1);
				int cnt=0;
				for(int j=1;j<=p;++j){
					if(!done[num[j]]){
						if(cnt>=3){
							continue;
						}
						switch(num[j]){
							case 1:printf("A");break;
							case 2:printf("B");break;
							case 3:printf("C");break;
							case 4:printf("D");break;
						}
						++cnt;
						done[num[j]]=true;
					}
				}
				printf(" ");
			}
			break;
	}
	system("pause");
	return 0;
}