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

int main(void)
{
    int i;
    long N;
    long term;
    int *a;
    scanf("%ld",&N);
    a=(int *)malloc(N*sizeof(int));
    for(i=0;i<N;i++){
        scanf("%ld",&term);
        a[i]=(int)(1+(int)(sqrt(8*term-7))-sqrt(8*term-7));

    }
    for(i=0;i<N;i++)printf("%2d",a[i]);
    return 0;
}

Thank you!

a[i]=(int)(1+(int)(sqrt((float)(8*term-7)))-sqrt((float)(8*term-7)));

but
long int have 4 bytes
and, 2^31*8 = overflow ;)

> a[i]=(int)(1+(int)(sqrt((float)(8*term-7)))-sqrt((float)(8*term-
7)));
>
> but
> long int have 4 bytes
> and, 2^31*8 = overflow ;)
thank you!