HDU5323.Solve this interesting problem

来源：互联网发布：python array split 编辑：程序博客网时间：2024/05/18 02:22

首先如果给出[L,R],那么它一定是由[2*L-R-1,R]或者[2*L-R-2,R]或者
[L,2*R-L]或者[L,2*R-L+1]变化而来
其次考虑他的剪枝,设len=R-L+1,如果L

#include <map>#include <set>#include <stack>#include <queue>#include <cmath>#include <ctime>#include <vector>#include <cstdio>#include <cctype>#include <cstring>#include <cstdlib>#include <iostream>#include <algorithm>using namespace std;#define INF 0x3f3f3f3f#define inf -0x3f3f3f3f#define lson l,m,rt<<1#define rson m+1,r,rt<<1|1#define mem0(a) memset(a,0,sizeof(a))#define mem1(a) memset(a,-1,sizeof(a))#define mem(a, b) memset(a, b, sizeof(a))typedef long long ll;const int maxn=100000+100;int ans;void dfs(int L,int R,int cnt){    if(cnt>=13)        return ;    if(L<0)        return ;    if(L==0){        ans=min(ans,R);        return ;    }    int len=R-L+1;    if(L<len)        return ;    if(R>L){        dfs(L,2*R-L,cnt+1);    }    dfs(L,2*R-L+1,cnt+1);    dfs(2*L-R-2,R,cnt+1);    dfs(2*L-R-1,R,cnt+1);}int main(){    int L,R;    while(scanf("%d%d",&L,&R)!=EOF){        ans=INF;        dfs(L,R,0);        printf("%d\n",ans==INF? -1:ans);    }    return 0;}

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