A. Vova and Train 思維+技巧
Vova plans to go to the conference by train. Initially, the train is at the point 11 and the destination point of the path is the point LL. The speed of the train is 11 length unit per minute (i.e. at the first minute the train is at the point 11, at the second minute — at the point 22 and so on).
There are lanterns on the path. They are placed at the points with coordinates divisible by vv (i.e. the first lantern is at the point vv, the second is at the point 2v2v and so on).
There is also exactly one standing train which occupies all the points from ll to rr inclusive.
Vova can see the lantern at the point pp if pp is divisible by vv and there is no standing train at this position (p∉[l;r]p∉[l;r]). Thus, if the point with the lantern is one of the points covered by the standing train, Vova can't see this lantern.
Your problem is to say the number of lanterns Vova will see during the path. Vova plans to go to tt different conferences, so you should answer tt independent queries.
Input
The first line of the input contains one integer tt (1≤t≤1041≤t≤104) — the number of queries.
Then tt lines follow. The ii-th line contains four integers Li,vi,li,riLi,vi,li,ri (1≤L,v≤1091≤L,v≤109, 1≤l≤r≤L1≤l≤r≤L) — destination point of the ii-th path, the period of the lantern appearance and the segment occupied by the standing train.
Output
Print tt lines. The ii-th line should contain one integer — the answer for the ii-th query.
Example
input
4 10 2 3 7 100 51 51 51 1234 1 100 199 1000000000 1 1 1000000000
output
3 0 1134 0
Note
For the first example query, the answer is 33. There are lanterns at positions 22, 44, 66, 88 and 1010, but Vova didn't see the lanterns at positions 44and 66 because of the standing train.
For the second example query, the answer is 00 because the only lantern is at the point 5151 and there is also a standing train at this point.
For the third example query, the answer is 11341134 because there are 12341234 lanterns, but Vova didn't see the lanterns from the position 100100 to the position 199199 inclusive.
For the fourth example query, the answer is 00 because the standing train covers the whole path.
題意:從1開始為起點到L為終點,每個點有一個燈籠,l~r區間內的燈籠被遮擋住,問posion/v為整數的位置時有多少燈籠可以被看到。
分析:如果通過一個一個的列舉必定會超時,親身經歷,各種優化反正失敗了。通過技巧先算出所有滿足position/v為整數的所有點-(然後算出從[1~r]所有滿足的點-從[1~l]所有滿足的點+(l%v==0)),注意對l點進行特判。
程式碼:
#include<iostream>
#include<cstdio>
using namespace std;
int main()
{
int t,over,L,R,V,ans;
scanf("%d",&t);
while(t--)
{
scanf("%d%d%d%d",&over,&V,&L,&R);
ans=over/V;
ans-=R/V-L/V;
if(L%V==0) ans--;
printf("%d\n",ans);
}
return 0;
}