Tính S(n) = 1 – 1/(1 + 2) + 1/(1 + 2 + 3) + … + (-1)^n+1 * 1/(1 + 2 + 3+ … + n)

#include<stdio.h>
#include<conio.h>
#include<math.h>
int main()
{
	int i, n;
	float S, P;
	S = 0;
	P = 0;
	i = 1;
	do
	{
		printf("\nNhap n: ");
		scanf("%d", &n);
		if(n < 1)
		{
			printf("\nN phai lon hon hoac bang 1. Xin nhap lai !");
		}
	}while(n < 1);

	while(i <= n)
	{
		P = P + i;
		S = S + 1 * pow(-1, (float)(1 + i))/ P;
		i++;
	}
	printf("\nTong la %f", S);

	getch();
	return 0;
}