Very simple computer secondary programming, why the results of the program will not output it

Write up the standard answer also do not output, the purpose is to find m! /{(m-n)! *n! }

#include<stdio.h>
float fun(int m, int n)
{
    int i;
    float j=1,k=1,h=1;
    float x;
    for(i=m;i>=1;i--)
        j*=i;
    for(i=n;i>=1;i--)
        k*=i;
    for(i=m-n;k>=1;i--)
        h*=i;
    x=j/(k*h);
    return x;
}
int main()
{
    int m=12,n=8;
    float s=fun(m,n);
    printf("%f",s);
    return 0;
}

Please see what the problem is. Thank you.

Very simple computer secondary programming, why the results of the program will not output it

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0 Answer

gyh33900 注册会员
2023-02-25 12:11

This answer quotes ChatGPT

When calculating combination numbers, the use of integer variables may cause the result to overflow. Therefore, in this case, consider using long integers or floating-int variables.

In the given code, we use floating-point variables to calculate, but in the third loop, there is an error in the condition for calculating the factorial, which should be i > = h instead of k > = 1.

Therefore, the modified code looks like this:


#include 

float fun(int m, int n)
{
    int i;
    float j = 1, k = 1, h = 1;
    float x;

    for (i = m; i >= 1; i--)
        j *= i;

    for (i = n; i >= 1; i--)
        k *= i;

    for (i = m - n; i >= 1; i--)
        h *= i;

    x = j / (k * h);

    return x;
}

int main()
{
    int m = 12, n = 8;
    float s = fun(m, n);
    printf("%f", s);

    return 0;
}

In this code, we first use a loop to calculate m! n! And m minus n factorial. And then you divide them to get the number of combinations. Because floating point variables are used for computation, overflow problems of integer variables are avoided

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dlstonefly 注册会员
2023-02-25 12:11

the reference answer GPT ᴼ ᴾ ᴱ ᴺ ᴬ ᴵ < br / > in your fun function, the third loop termination condition is not correct. It should be i >. = 1 instead of k > = 1. Therefore, when n > When m - n, the initial value of h is 0, causing the function to return a value of NaN, or "Not a Number", so your program has no output.

After modifying the terminating condition of the third loop in the fun function, your program should look like this:

#include

float fun(int m, int n) {
    int i;
    float j = 1, k = 1, h = 1;
    float x;
    for (i = m; i >= 1; i--)
        j *= i;
    for (i = n; i >= 1; i--)
        k *= i;
    for (i = m - n; i >= 1; i--)
        h *= i;
    x = j / (k * h);
    return x;
}

int main() {
    int m = 12, n = 8;
    float s = fun(m, n);
    printf("%f", s);
    return 0;
}

Then you can print the result correctly.

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Publish Time: 2023-02-25 12:11

Update Time: 2023-02-25 12:11