zoj Treasure Hunt IV

Treasure Hunt IV

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Time Limit: 2 Seconds       Memory Limit: 65536 KB

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Alice is exploring the wonderland, suddenly she fell into a hole, when she woke up, she found there are b - a + 1 treasures labled a from b in front of her.
Alice was very excited but unfortunately not all of the treasures are real, some are fake.
Now we know a treasure labled n is real if and only if [n/1] + [n/2] + ... + [n/k] + ... is even.
Now given 2 integers a and b, your job is to calculate how many real treasures are there.

Input

The input contains multiple cases, each case contains two integers a and b (0 <= a <= b <= 2⁶³-1) seperated by a single space. Proceed to the end of file.

Output

Output the total number of real treasure.

Sample Input

0 2

0 10

Sample Output

1

6

 

 1 #include<iostream>

 2 #include<stdio.h>

 3 #include<cstring>

 4 #include<cstdlib>

 5 #include<math.h>

 6 using namespace std;

 7 typedef unsigned  long long LL;

 8 

 9 LL solve(LL n)

10 {

11     LL m = (LL)sqrt(n*1.0);

12     LL sum=0;

13     if(m%2==0) sum = n-m*m;

14     if(m%2==1) m++;

15     LL j=m/2;

16     sum=sum-j+2*j*j;

17    // sum=sum+2*j*j-j;

18     return sum;

19 }

20 int main()

21 {

22     LL n,m;

23     while(scanf("%llu%llu",&n,&m)>0)

24     {

25         n++,m++;

26         LL ans=solve(n-1);

27         LL cur =solve(m);

28         printf("%llu\n",cur-ans);

29     }

30     return 0;

31 }