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  • 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.

    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.

    Example
    Input
    2
    4
    1000000000
    
    Output
    -4
    499999998352516354
    
    Note

    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
    ",sum);
    		
    	}
    }






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  • 原文地址:https://www.cnblogs.com/-xiangyang/p/9220273.html
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