题目
1621: [Usaco2008 Open]Roads Around The Farm分岔路口
Time Limit: 5 Sec Memory Limit: 64 MB
Submit: 561 Solved: 407
[Submit][Status]
Description
约翰的N(1≤N≤1,000,000,000)只奶牛要出发去探索牧场四周的土地．她们将沿着一条路走，一直走到三岔路口（可以认为所有的路口都是这样的）．这时候，这一群奶牛可能会分成两群，分别沿着接下来的两条路继续走．如果她们再次走到三岔路口，那么仍有可能继续分裂成两群继续走． 奶牛的分裂方式十分古怪：如果这一群奶牛可以精确地分成两部分，这两部分的牛数恰好相差K(1≤K≤1000)，那么在三岔路口牛群就会分裂．否则，牛群不会分裂，她们都将在这里待下去，平静地吃草． 请计算，最终将会有多少群奶牛在平静地吃草．
Input
两个整数N和K.
Output
最后的牛群数．
Sample Input
6 2
INPUT DETAILS:
There are 6 cows and the difference in group sizes is 2.
INPUT DETAILS:
There are 6 cows and the difference in group sizes is 2.
Sample Output
3
OUTPUT DETAILS:
There are 3 final groups (with 2, 1, and 3 cows in them).
6
/ \
2 4
/ \
1 3
OUTPUT DETAILS:
There are 3 final groups (with 2, 1, and 3 cows in them).
6
/ \
2 4
/ \
1 3
HINT
6只奶牛先分成2只和4只．4只奶牛又分成1只和3只．最后有三群奶牛．
题解
直接模拟就行了，一旦奶牛数不足k+2或者奶牛数无法被分成x,x+k时中止。
代码
/*Author:WNJXYK*/
#include<cstdio>
#include<iostream>
#include<cstring>
#include<string>
#include<algorithm>
#include<queue>
#include<set>
#include<map>
using namespace std; #define LL long long
#define Inf 2147483647
#define InfL 10000000000LL inline void swap(int &x,int &y){int tmp=x;x=y;y=tmp;}
inline void swap(LL &x,LL &y){LL tmp=x;x=y;y=tmp;}
inline int remin(int a,int b){if (a<b) return a;return b;}
inline int remax(int a,int b){if (a>b) return a;return b;}
inline LL remin(LL a,LL b){if (a<b) return a;return b;}
inline LL remax(LL a,LL b){if (a>b) return a;return b;} int n,k; int solve(int x){
if (x<k+2 || (x+k)%2==1) return 1;
return solve((x+k)/2)+solve((x-k)/2);
}
int main(){
scanf("%d%d",&n,&k);
printf("%d\n",solve(n));
return 0;
}