请教高手个C语言问题

/*终于弄出来了，测试通过
其实有规律的，看每行的起始值，之间的差值是递增的，每行里面也是。*/

#include <stdio.h>

int main(int argc, char **argv)
{
int N = 5, i, j;
int start, interval, last;
/*start: start number of each line*/
/*interval: the defference between each pair of neibough numbers*/
/*last: the number last printed*/
printf("Enter N:\n");
do
{
scanf("%d", &N);
}
while(N <= 0);

start = 1;
for(i = 1; i <= N; i++)
{/*total number of lines*/
printf("%d ", start);/*print the first one*/
last = start;

interval = i + 1;
for(j = 2; j <= N - i + 1; j++)
{/*numbers of each line*/
last += interval;
printf("%d ", last);
interval++;
}
printf("\n");
start += i;
}

return 0;
}

#include "stdio.h"
main()
{