HDU6046-hash

hash

                                                                   Time Limit: 10000/5000 MS (Java/Others)    Memory Limit: 262144/262144 K (Java/Others)
                                                                                               Total Submission(s): 502    Accepted Submission(s): 155

Problem Description

Qscqesze is busy at data cleaning.
One day,he generates a large matrix by Jenkins one-at-a-time hash:
inline unsigned sfr(unsigned h, unsigned x) {
  return h >> x;
}
int f(LL i, LL j) {
  LL w = i * 1000000ll + j;
  int h = 0;
  for(int k = 0; k < 5; ++k) {
    h += (int) ((w >> (8 * k)) & 255);
    h += (h << 10);
    h ^= sfr(h, 6);
  }
  h += h << 3;
  h ^= sfr(h, 11);
  h += h << 15;
  return sfr(h, 27) & 1;
}
Obviously,it's a 1e6*1e6 matrix.The data is at row i column j is f(i,j).Note that i and j are both numbered from 1.
Then he gets some matrices sized 1e3*1e3 from the matrix above.But he forgets their original postion.Can you help him to find them out?You just are asked to tell Qscqesze the left-top corner's postion.

 

Input

The first line is the number of test cases T (T<=3). 
Here come with T cases.Each case is consist of 1000 0/1-strings sized 1000.
For convenience,the sample input is 10*10.And the real testcase is 1e3*1e3.

 

Output

For each test case, output a single line "Case #x :y z", where x is the case number, starting from 1. And y z is the answer.

 

Sample Input

10000011100000011001101111111000011110010011010101010010010010100111110111100101000111011101100110100

 

Sample Output

Case #1 :123456 234567

 

Source

2017 Multi-University Training Contest - Team 2

 

题意：给出一个1e3*1e3的小矩阵，让你在一个1e6*1e6的矩形内它，并输出左上端点

解题思路：先在1e3*1e3的小矩阵中处理出所有8*8的识别矩阵。然后遍历1e6*1e6的矩阵，遍历时不需要遍历所有点，只需要行之间隔1000，列之间隔1000即可（因为这样里面至少覆盖了一个识别矩阵），然后处理出这个以这个点位左上端点的8*8的小矩阵，然后判断在1e3*1e3的矩阵中能否找到这个矩阵即可

#include <iostream>#include <cstdio>#include <cstring>#include <string>#include <algorithm>#include <map>#include <set>#include <stack>#include <queue>#include <vector>#include <bitset>#include <unordered_map>#include <functional>using namespace std;#define LL long longconst int INF = 0x3f3f3f3f;unordered_map<LL,pair<int,int>>mp;char ch[1009][1009];inline unsigned sfr(unsigned h, unsigned x){    return h>>x;}int f(LL i, LL j){    LL w=i*1000000ll+j;    int h=0;    for(int k=0;k<5;k++)    {        h+=(int)((w>>(8*k))&255);        h+=(h<<10);        h^=sfr(h,6);    }    h+= h<<3;    h^=sfr(h,11);    h+=h<<15;    return sfr(h,27)&1;}int main(){    int t,cas=0;    scanf("%d",&t);    while(t--)    {        for(int i=1;i<=1000;i++)scanf("%s",ch[i]+1);        mp.clear();        for(int i=1;i<=993;i++)        {            for(int j=1;j<=993;j++)            {                LL temp=0;                for(int k=0;k<8;k++)                    for(int p=0;p<8;p++)                    {                        temp<<=1;                        if(ch[i+k][j+p]=='1') temp|=1;                    }                mp[temp]=make_pair(i,j);            }        }        int flag=0;        for(int i=1;i<=1e6;i+=992)        {            for(int j=1;j<=1e6;j+=992)            {                LL temp=0;                for(int k=0;k<8;k++)                    for(int p=0;p<8;p++)                    {                        temp<<=1;                        if(f(i+k,j+p)) temp|=1;                    }                if(mp.find(temp)!=mp.end())                {                    pair<int,int> ans=mp[temp];                    printf("Case #%d :%d %d\n",++cas,i-ans.first+1,j-ans.second+1);                    flag=1;break;                }            }            if(flag) break;        }    }    return 0;}