I have written this block of code but it is consuming lots of time to calculate... Can you help me finding out an efficient way to do it?

int tag;
int* factors(int n)
{
    int a[1000000];
    for(int i=1;i<=n/2;i++)
        if(n%i==0)
            a[++tag]=i;
    a[++tag]=n;
    return(a);
}

This brute force method is very hefty in terms of complexity... Is there any better feasible solution to this problem?

c algorithm numbers factors
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