Zzuli OJ 1041: Sequence sum 2

Source: Internet
Author: User

Enter an integer n, output sequence 1-1/3+1/5-...... The and of the first n items. Input

Enter only one integer n.

The result retains 2 as a decimal and occupies a single row. Sample Input 3 sample Output 0.87 HINT


#include <stdio.h>

int main ()
    int i, n;
    Double sum, Deno, flag;

    scanf ("%d", &n);
    sum = 0.0;
    Deno = 1.0; The initial value is the denominator of the first item
    flag = 1.0;  The initial value is the symbol for the first item for

    (i = 1; I <= n; i++)//Loop n times
        sum + = Flag/deno; calculate and add the current item
        Deno + = 2;  Computes the next denominator
        flag =-flag//calculates the next symbol

    printf ("%.2f\n", sum);
    return 0;

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