7-15 计算圆周率 （15 分)

输入样例：
0.01
输出样例：
3.132157

AC代码

#include <stdio.h>
int main(){
	double limit, pi, fenzi, fenmu, sum, temp1, sum1, temp2;
	fenzi = 1;
	temp1 = 1;
	temp2 = 3;
	fenmu = 3;
	sum = 1;
	sum1 = 1;
	scanf("%lf", &limit);
	while (sum1 > limit){
		sum1 = fenzi / fenmu;
		sum = sum + sum1;
		temp1++;
		temp2 = temp2 + 2;
		fenzi = fenzi * temp1;
 		fenmu = fenmu * temp2;
	}
    pi = sum * 2;
    printf("%.6f", pi);
    return 0;
}