2.11刷题

目录

计算三角形面积 - 洛谷

B2032 等差数列末项计算

B2034 计算 2 的幂

B2035 判断数正负

B2036 输出绝对值

---

计算三角形面积 - 洛谷

海伦公式，计算已知三角形三边的边长时可用。

#include<iostream> 
#include<math.h>
using namespace std;
int main(){
	double x1,y1,x2,y2,x3,y3;
	scanf("%lf %lf %lf %lf %lf %lf",&x1,&y1,&x2,&y2,&x3,&y3);
	double a,b,c,p;
	a=sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
	b=sqrt((x1-x3)*(x1-x3)+(y1-y3)*(y1-y3));
	c=sqrt((x3-x2)*(x3-x2)+(y3-y2)*(y3-y2));
	p=(a+b+c)/2;
	printf("%0.2lf",sqrt(p*(p-a)*(p-b)*(p-c)));
	
	return 0;
}

B2032 等差数列末项计算

#include<iostream>
using namespace std;

int main(){
    long long a,b,n;
    
    scanf("%lld %lld %lld",&a,&b,&n);
    printf("%lld",a+(n-1)*(b-a));
    return 0;
}

B2034 计算 2 的幂

#include<iostream>
#include<math.h>
using namespace std;
int main(){
	int n;
	scanf("%d",&n);
	long long x=pow(2,n);
	printf("%lld",x);
	
	return 0;
}

B2035 判断数正负

#include<iostream>
using namespace std;
int main(){
	int n; //这里的数据类型不能用long long，会报错
	scanf("%d",&n);
	if(n>0) printf("positive");
	else if(n==0)	printf("zero");
	else	printf("negative");
	
	return 0;
}

B2036 输出绝对值

#include<iostream>
using namespace std;
int main(){
	float n;
	scanf("%f",&n);
	if(n>=0)	printf("%0.2f",n);
	else	printf("%0.2f",-n)	;
	
	return 0;
}