Tricky Sum
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.
Input
2 4 1000000000
Output
-4 499999998352516354
The answer for the first sample is explained in the statement.
题意 计算-1-2+3-4+5+6+7-8........这个公式。
解法 将所有2的次方存起来。
#include<cstdio> long long a[40]; long long pow(int n) { if(n==0) return 1; else { long long k1=1; for(int i=0;i<n;i++) k1*=2; return k1; } } int main() { int t; scanf("%d",&t); for(int i=0;i<33;i++) a[i]=pow(i); while(t--) { long long n; scanf("%lld",&n); long long sum; sum=(1+n)*n/2; int i; for( i=0;i<33;i++) if(n<=a[i]) break; if(n==a[i]) i=i+1; long long sum1=0; for(int j=0;j<i;j++) sum1+=a[j]; sum=sum-sum1*2; printf("%lld\n",sum); } }