传送门:
http://codeforces.com/problemset/problem/598/A
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.
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).
Print the requested sum for each of t integers n given in the input.
2
4
1000000000
-4
499999998352516354
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 ",sum); } return 0; }