Question

编写程序，输入一个正整数n，计算1-2/3+3/5-4/7+5/9-6/11+···的前n项之和

Answer 1

int
main()
double
result;
int
i;
int
n;
scanf("%d\n",
n);
for
(i
=
1;
i
<=
n;
i++)
if
(i
%
2)
result
=
result
+
i
/
(2
*
i
-
1)
else
result
=
result
-
i
/
(2
*
i
-
1)
printf
("result
=
%d\n",
result);
return
0;
}

Answer 2

int main()
double result;
int i;
int n;
scanf("%d\n", n);
for (i = 1; i <= n; i++)
if (i % 2)
result = result + i / (2 * i - 1)
else
result = result - i / (2 * i - 1)

printf ("result = %d\n", result);
return 0;
}