Poj2315 football games

Problem description ：

Alice and Bob both love football very much , Both are pioneers . They are all good at football control . The day after a football match , They had an interesting game , They shot the football directly at the goal . In front of the goal N A football , They take turns in this game . for example , If it's Alice's turn , Alice can choose some football （ The number of football must be equal to or less than M） And shoot them forward . Because the quality of football is not very good , Football is not a complete sphere , Only integer multiples of its perimeter can be scrolled . And because of their friction and force limitations , They can't shoot the football more than L Centimeters away . Of course , They know that the radius of football is R centimeter . Alice and Bob like this game very much . If both of them have infinite intelligence and accurate shooting skills , Can you guess who can win the football match ？ By the way , Although Alice is as strong as Bob , But Alice is a girl , So she will do it first .

analysis ： The main idea of the topic is that the two players take turns from N Pick out no more than M Shot , The radius of each sphere is R, Off goal S. You can only kick L Within the distance . The one who scores the last goal wins , Ask who has a winning strategy ？ We found that after processing the data , The title is equivalent to giving n Rubble , The maximum number of stones in each pile is k A stone , At most m A game problem of stone pile operation , First of all, we stack each pile of stones right k+1 Modular simplification , The practice of taking stones from a pile of stones is to stack all stones sg Value for xor Operation result sg value ,xor Also known as semi addition , Only add without carry , For selection m The game of piling stones is ours xor It's about m+1 Half addition operation under base , So we calculate this in bits sg value , simulation m+1 The answer can be obtained by half addition operation under base .

Input ：

The input consists of several cases , Each case contains two lines .
For each test case , The first line contains 4 It's an integer N、M、L and R（1 <= M <= N <= 30, 0 < L < 100000000, 0 < R < 10000）, Separate... With a space .N It's the number of football ,M It is the maximum number of football a player can shoot in a round ,L Is the maximum distance a player can shoot ,R Is the radius of football .
The next line contains N A digital ,S(1), S(2), ..., S(N) (0 < S(i) < 100000000), They describe the distance between football and goal .

Output ：

For each case , The output contains a line describing the name of the winner .

Sample input ：

 

Sample output ：

  Program code ：

#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
const int N=30;
const double PI=acos(-1.0);
int n,m,l,r,a[N],sg[N];
int dis(int s)                        // See if you can score 
{
     return (int)(s/(2*PI*r))+1;
}
bool solve(){                        // Game function 
    memset(sg,0,sizeof(sg));
    int k=dis(l);
    for(int i=0;i<n;i++)
      for(int j=0,g=dis(a[i])%k;sg[j]+=g&1,g;j++,g>>=1);
        for(int i=0;i<30;i++)
           if(sg[i]%(m+1))
               return 1;
    return 0;
}
int main(){
    while(~scanf("%d%d%d%d",&n,&m,&l,&r)){
        for(int i=0;i<n;i++)
             scanf("%d",&a[i]);
             puts(solve()?"Alice":"Bob");
    }
    return 0;
}

yjg