CodeForces - 598A Tricky Sum (数学,快速幂的运用)

传送门:

http://codeforces.com/problemset/problem/598/A

A. Tricky Sum
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard 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.

Examples
Input
Copy
2
4
1000000000
Output
Copy
-4
499999998352516354
Note

The answer for the first sample is explained in the statement.

分析:

题意:

先输入一个T,表示有几组输入,再输入一个n,表示要计算n的和sum。

计算规则为,从1---n这n个数中任意一个数m,如果m这个数是2的次方的话,sum+=(-m),否则sum+=m。

思路:

先求出总的和sum,再用快速幂,求出所有是2的次方的数的和num,最后求差即可sum=sum-2*num。

code:

#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
LL qm(int n,int m)//快速幂
{
    LL s=1,x=n;
    while(m)
    {
        if(m&1)
        {
            s*=x;
        }
        x*=x;
        m>>=1;
    }
    return s;
}
int main()
{
    int t;
    cin>>t;
    LL n;
    LL sum;
    while(t--)
    {
        scanf("%I64d",&n);
        sum=n*(n+1)/2;//等差数列求和公式
        for(int i=0;qm(2,i)<=n;i++)
        {
            sum-=(2*qm(2,i));
        }
        printf("%I64d\n",sum);
    }
    return 0;
}

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转载自www.cnblogs.com/yinbiao/p/9365127.html