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Time Limit:2000MS Memory Limit:65536KB 64bit IO Format:%lld & %llu
Description
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
题意：给你一个Long long范围的区间，然后问里面有多少个数，满足n/1+n/2+n/k……加起来等于一个偶数
题解：首先打表，然后我们发现这种数是扎堆存在的，[0,1),[4,9),[16,25),……
然后我们就这样子找规律，然后一个等差数列求和就好啦！
LL solve(LL n) { LL m = (LL)sqrt(n*1.0); LL sum=0; if(m%2==0) sum = n-m*m; if(m%2==1) m++; LL j=m/2; sum=sum-j+2*j*j; // sum=sum+2*j*j-j; return sum; } int main() { LL n,m; while(scanf("%llu%llu",&n,&m)>0) { n++,m++; LL ans=solve(n-1); LL cur =solve(m); printf("%llu\n",cur-ans); } return 0; }
zoj 3629 Treasure Hunt IV 打表找规律
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原文地址：http://www.cnblogs.com/qscqesze/p/4320225.html
