A positive integer is called a 2-3-integer, if it is equal to 2x·3y for some non-negative integers x and y. In other words, these integers are such integers that only have 2 and 3 among their prime divisors. For example, integers 1, 6, 9, 16 and 108 — are 2-3 integers, while 5, 10, 21 and 120 are not.
Print the number of 2-3-integers on the given segment [l, r], i. e. the number of sich 2-3-integers t that l ≤ t ≤ r.
The only line contains two integers l and r (1 ≤ l ≤ r ≤ 2·109).
Print a single integer the number of 2-3-integers on the segment [l, r].
1 10
7
100 200
5
1 2000000000
326
In the first example the 2-3-integers are 1, 2, 3, 4, 6, 8 and 9.
In the second example the 2-3-integers are 108, 128, 144, 162 and 192.
这道题,不难,但是lowlow的我当时确实是没做出来,我写这篇,只是为了再一次告诉自己,你真的很low,真的需要努力,不然这么水的题都做不出来!
代码:
#include<iostream>
typedef long long LL;
using namespace std;
int main()
{
LL l,r,ans=0,i,j;
cin>>l>>r;
for(i=1;i<=r;i*=2)
{
for(j=1;j<=r;j*=3)
{
if(l<=i*j&&i*j<=r)
ans++;
}
}
cout<<ans<<endl;
}