7-12 sdut-循环-9 求定积分 (10 分)

题目

代码

import java.util.Scanner;

class Main {
	public static void main(String[] args) {
   Scanner sc =new Scanner(System.in); 
   double a,b,interval,sum;
   int n,i;
   double left;
   while(sc.hasNext())
   {
	   a=sc.nextDouble();
	   b=sc.nextDouble();
	   n=sc.nextInt();
	   interval=(b-a)/n;
	   sum=0;
	   
	   for(i=0,left=a;i<n;i++)
	   {
		   double tmp=(left*left+(left+interval)*(left+interval))*interval/2;
		   /*
		    * 定积分约等于求面积
		    * 左边高：left*left
		    * 右边高：(left+interval)*(left+interval)
		    * 长度：interval
		    * 梯形求面积：记得除以2
		    */
		   sum+=tmp;
		   left+=interval;
	   }
	   System.out.printf("%.3f\n",sum);
   }
   
   sc.close();
   
}
}