第一题

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#include"stdio.h"

int count(int x){
	//求小于x的所有因子之和
	int sum,i;
	sum=1;
	for(i=2;i<x;i++){
		if(x%i==0)
			sum += i;
	}
	return sum;
}

int main(){
	int i;
	for(i=1;i<=10000;i++){
		if(i==count(i))
			printf("%2d,",i);
	}

	return 0;
}

第二题

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#include"stdio.h"
#include"math.h"

int is_threeANgle(int a,int b,int c){
	if(a+b>c && a+c>b && b+c>a)
		return 1;
	else return 0;
}

int main(){
	int a,b,c,s;
	double area;
	printf("输入三条边:");
	scanf("%d %d %d",&a,&b,&c);
	if(is_threeANgle(a,b,c)){
		if(a==b &&b==c)
			printf("等边三角形\n");
		else if(a==b || a==c || b==c)
			printf("等腰三角形\n");
		else if(a*a==b*b+c*c || b*b==a*a+c*c || c*c==a*a+b*b)
			printf("直角三角形\n");
		else printf("一般三角形\n");
		s=(a+b+c)/2;
		area=sqrt((double)s*(s-a)*(s-b)*(s-c));
		//sqrt(double)只有这个用法，不支持sqrt(int)
		
		printf("三角形面积:%f\n",area);
	}
	else printf("不能组成三角形\n");
	return 0;
}

第三题

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#include"iostream"

using namespace std;

class vehicle {
protected:
	int wheels;  //车轮数
	float weight;  //重量
public:
	//vehicle(int WH,float WE);      //构造函数
	void init(int wheels,float weight);  
	float get_weight();   //返回重量
	int get_wheels();    //返回车轮数
	void print();    //输出车轮数和重量
};
/*
vehicle::vehicle(int WH,float WE){
	wheels=WH;
	weight=WE;
}*/
void vehicle::init(int wheels,float weight){
	this->wheels=wheels;
	this->weight=weight;
}
float vehicle::get_weight(){
	return this->weight;
}
int vehicle::get_wheels(){
	return this->wheels;
}
void vehicle::print(){
	cout<<"车轮数:"<<this->wheels<<"重量："<<this->weight<<endl;
}


class car:public vehicle {
private:
	int passenger;
public:
	//car(int WH,float WE,int PA);
	void init(int wheels,float weight,int passenger);
	int get_passenger();   //返回载人数
	void print();   //输出车轮数，重量和载人数
};
/*
car::car(int WH,float WE,int PA):vehicle(WH,WE){
	passenger=PA;
}*/
void car::init(int wheels,float weight,int passenger){
	this->wheels=wheels;
	this->weight=weight;
	this->passenger=passenger;
}
int car::get_passenger(){
	return this->passenger;
}
void car::print(){
	cout<<"车轮数:"<<this->wheels<<"重量："<<this->weight<<"载人数："<<this->passenger<<endl;
}


int main(){

	car c;
	c.init(4,200,4);
	c.print();
	
	return 0;
}