求1到N范围的阶乘

Question

试图编写一个程序，将找到阶乘的范围内的数字从1到N，N是最后的数字找到阶乘，我写了一个非递归program.it只适用于整数1和2在循环中，我不知道如何修复它，因为逻辑似乎很好，我也有点还是一个初学者，所以我知道我可能错过了一些明显的东西，但在任何情况下，这里的代码：

 #include<stdio.h>



int main() {
    
    int firstnumber;
    int finalnumber;

printf("this is a program to calculate the factorial of numbers between 1 to N\n"); 


printf("please enter the final number : ");

 
scanf("%d",&finalnumber);

int i;
int factorial=1;


for (firstnumber=1;firstnumber<=finalnumber;firstnumber++) {
    printf("the factorial of %d is : ",firstnumber);
 
 
    for (i=1;i<=firstnumber;i++) {
        factorial=factorial*i;
    }

    printf("%d \n ",factorial);
}

return 0;
}

Answer 1

您的两个循环是多余的：您可以从number-1的阶乘中计算number的阶乘

这是一个只有一个循环的程序。复杂性O（N）。

注意，使用int会很快溢出。

#include<stdio.h>

int main() {
    
    int number;
    int finalnumber;

    printf("this is a program to calculate the factorial of numbers between 1 to N\n"); 

    printf("please enter the final number : ");

    scanf("%d",&finalnumber);

    int factorial = 1;

    for (number=1; number<=finalnumber; number++) {
        printf("the factorial of %d is : ",number);
        factorial *= number;
        printf("%d \n",factorial);
    }

    return 0;
}

Answer 2

您需要在每次计算之前初始化factorial。

int i;
// delete this
//int factorial=1;


for (firstnumber=1;firstnumber<=finalnumber;firstnumber++) {
    printf("the factorial of %d is : ",firstnumber);

    // move the declaration here
    int factorial=1;

    for (i=1;i<=firstnumber;i++) {
        factorial=factorial*i;
    }

    printf("%d \n ",factorial);
}