题解： Codeforces 598A Tricky Sum （水）

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题目

A. Tricky Sum
time limit per test1 second
memory limit per test256 megabytes
inputstandard input
outputstandard output
In this problem you are to calculate the sum of all integers from 1 to n, but you should take all powers of two with minus in the sum.

For example, for n = 4 the sum is equal to  - 1 - 2 + 3 - 4 =  - 4,
because 1, 2 and 4 are 20, 21 and 22 respectively.

Calculate the answer for t values of n.

Input
The first line of the input contains a single integer t
(1 ≤ t ≤ 100) — the number of values of n to be processed.

Each of next t lines contains a single integer n (1 ≤ n ≤ 109).

Output

Print the requested sum for each of t integers n given in the input.

Sample test(s)

input

2

4

1000000000

output

-4

499999998352516354

分析

前N项中非2的级数的和减去2的级数

先看前半部分 直接用公式 n * (n + 1) / 2

后半部分用循环

控制循环的终止条件是 2 ^ i > n

上代码

#include<cstdio>#include<cstring>#include<algorithm>#include<cmath>using namespace std;long long num;long long fin;int main(void){    int t;    while (scanf("%d", &t) != EOF)    {        while (t--)        {            scanf("%lld", &num);            fin = num * (num + 1) / 2;            for (int i = 0; pow(2, i) <= num; i++)                fin -= (2 * pow(2, i));            printf("%lld\n", fin);        }    }    return 0;}