View Code of Problem 18

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int n;
    int i;
    int a[10000];
    a[0]=0;
    a[1]=0;
    a[2]=1;
    for(i=3;i<10000;i++)
    {
        a[i]=a[i-1]+i-1;//a[3]=3 a[4]=6
    }
    while(scanf("%d",&n)!=EOF)
    {
        int sum;
        sum=a[(n+1)/2]+a[n-(n+1)/2];
        printf("%d\n",sum);
    }
    return 0;
}