c语言阶乘 ii多测试,C语言经典题目:求阶乘n!=n*(n-1)*...*1,阶乘和s=1!+(2)!+(3)!+...+n!...
1.求阶乘n!=n*(n-1)*...*1
思路:利用递推,迭代;
找规律:f(1)=1;f(2)=2*1;f(3)=3*2*1=3*(f(2));
一般公式:f(n)=n*f(n-1)
float fac(int n)
{
//求n!=n*(n-1)*...*1;
if (n == 1 || n == 0)
{
return 1;
}
return n * fac(n - 1);
}
2.计算s=1!+(2)!+(3)!+...+n!
float getfac_s(int n)
{
//计算s=1!+(2)!+(3)!+...+n!
float fac(int n);//声明
float sum = 0;
int i;
for (i = 1; i <= n; i++)
{
sum += fac(i);
}
return sum;
}
3.s=n!+(n+1)!+(n+2)!+...+m!
float getfac_s(int m, int n)
{
//计算s=n!+(n+1)!+(n+2)!+...+m!
int i;
float s = 1, sum = 0;
for (i = 1; i <= m; i++)
{
s = s * i;
if (i >= n)
{
sum += s;
}
}
return sum;
}
4.求分式e=1+1/1!+1/2!+...+1/n!
float getfac_e(int n) {
//分式求值,记得要用浮点型
//e=1+1/1!+1/2!+...+1/n!;
int i;
float e = 1, t;//项
for (i = 1; i <= n; i++)
{
t = float(1.0) / fac(i);
e += t;
}
return e;
}