Clock Pictures（kmp + Contest2075

Problem H: Clock Pictures

Time Limit: 3 Sec  Memory Limit: 128 MB
Submit: 73  Solved: 18
[Submit][Status][Web Board]

Description

Input

Output

Sample Input

6
1 2 3 4 5 6
7 6 5 4 3 1

Sample Output

impossible

HINT

题意：给你角度，问你通过旋转a图和b图能否重合；

思路：KMP；（比赛的时候，忘记是环了。。。还好队友给力！）

我的代码：

#include<stdio.h>
#include<algorithm>
#include<string.h>
#define mmax 200005
#define mod 360000
#define mem(a) memset(a,0,sizeof(a));
using namespace std;
int a[mmax],b[mmax],nnext[mmax];
int c[mmax*2];
int t,n;
void getnext()
{
    int i=0,k=-1;
    nnext[0]=-1;
    int len=n-1;
    while(i<len)
    {
        if(a[i]==a[k]||k==-1)
        {
            i++;
            k++;
            nnext[i]=k;
        }
        else
            k=nnext[k];
    }
}
void kmp()
{
    int i=0,j=0;
    int lena=n-1;
    int lenc=2*n-1;
//    int cnt=0;
    while(i<lenc&&j<lena)
    {
        if(a[j]==c[i]||j==-1)
        {
            i++;
            j++;
        }
        else
            j=nnext[j];
    }
    if(j!=lena)
        t=1;
    //else
  //      printf("i=%d	j=%d
",i,j);
}

int main()
{
    int i;
    while(scanf("%d",&n)!=EOF)
    {
        mem(a);
        mem(b);
        mem(c);
    //    mem(c);
        for(i=0;i<n;i++)
            scanf("%d",&a[i]);
        for(i=0;i<n;i++)
            scanf("%d",&b[i]);
        sort(a,a+n);
        sort(b,b+n);//printf("%d	%d
",a[i],b[i]);
        c[n-1]=(b[0]-b[n-1]+mod)%mod;
        for(i=1;i<n;i++)
        {
            a[i-1]=(a[i]-a[i-1]+mod)%mod;
            b[i-1]=(b[i]-b[i-1]+mod)%mod;
            c[i-1]=c[i-1+n]=b[i-1];
        }

        getnext();
        t=0;
        kmp();
        if(t)printf("impossible
");
        else printf("possible
");
    }
    return 0;
}

队友代码：

#include <iostream>
#include <stdio.h>
#include <string.h>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <vector>
#include <math.h>
#include <algorithm>
using namespace std;
#define ls 2*i
#define rs 2*i+1
#define up(i,x,y) for(i=x;i<=y;i++)
#define down(i,x,y) for(i=x;i>=y;i--)
#define mem(a,x) memset(a,x,sizeof(a))
#define w(a) while(a)
#define LL long long
const double pi = acos(-1.0);
#define Len 200005
#define mod 360000
const int INF = 0x3f3f3f3f;
#define exp 1e-6

int n,a[Len],b[Len],s[Len*2],next1[Len];

void get_next()
{
    next1[0] = 0;
    int i;
    up(i,2,n-1)
    {
        int t = i-1;
        t = next1[t];
        w(t!=0 && a[t+1]!=a[i]) t = next1[t];
        t++;
        if(a[t]==a[i]) next1[i] = t;
        else next1[i] = 0;
    }
}

int main()
{
    int i,j,k;
    w(~scanf("%d",&n))
    {
        up(i,0,n-1)
        scanf("%d",&a[i]);
        up(i,0,n-1)
        scanf("%d",&b[i]);
        sort(a,a+n);
        sort(b,b+n);
        down(i,n-1,1)
        a[i]=(a[i]-a[i-1]+mod)%mod;
        up(i,0,n-1)
        s[i]=s[i+n]=b[i];
        down(i,2*n-1,1)
        s[i]=(s[i]-s[i-1]+mod)%mod;
        int flag = 0;
        int pos = 1;
        get_next();

        up(i,1,2*n-1)
        {
            if(s[i]!=a[pos])
            {
                int tem = next1[pos-1];
                w(tem && s[i]!=a[tem+1])
                tem = next1[tem];
                tem++;
                if(a[tem]==s[i]) pos = tem+1;
                else pos = 1;
            }
            else pos++;
            if(pos == n)
            {
                flag = 1;
                break;
            }
        }
        printf("%d	%d
",i,n);
        printf("%s
",flag?"possible":"impossible");
    }

    return 0;
}

/**************************************************************
    Problem: 1581
    User: aking2015
    Language: C++
    Result: Accepted
    Time:276 ms
    Memory:5396 kb
****************************************************************/