"KMP algorithm" "Rabin-karp algorithm" [BeiJing2011] Matrix template

The algorithm does not say, anyway, is based on string matching. Compare the KMP and Rabin-karp algorithms here.

< method one >KMP algorithm.

592788

Lizitong

2462

Accepted

4828 KB

680 Ms

C++/edit

2349 B

2014-03-29 19:07:02

#include <cstdio> #include <cstring> #include <algorithm>using namespace Std;int N,m,a,b,q;char map[ 1001][1001],s[11][101][1001];int next[500001],pos[1001];void getfail (char p[],int next[]) {next[0]=next[1]=0;for (  int i=1;i<m;i++) {int j=next[i];  while (J&&p[i]!=p[j]) j=next[j];  if (P[i]==p[j]) next[i+1]=j+1;  else next[i+1]=0; }}int Find (char T[],char p[],int next[]) {N=strlen (T); M=strlen (P); Getfail (p,next); int j=0;for (int i=0;i<n;i++) {while (J&&p[j]!=t[i]) j=next[j];//if J becomes 0 still does not satisfy p[j]==t[i],   Only I until p[j]==t[i] is present.  if (P[j]==t[i]) j + +;  if (j==m) return i-m+1; }return-1;} int main () {scanf ("%d%d%d%d", &n,&m,&a,&b), for (int i=0;i<n;i++) scanf ("%s", Map[i]), scanf ("%d",    &AMP;Q), for (int i=1;i<=q;i++) for (int j=0;j<a;j++) scanf ("%s", S[i][j]), if (a==1) {for (int i=1;i<=q;i++) {    BOOL Flag=false;          for (int j=0;j<n;j++) if (Find (Map[j],s[i][0],next)!=-1) {flag=true;printf ("1\n");          Break    } if (!flag) printf ("0\n");  } return 0;  }for (int i=1;i<=q;i++) {bool Goal=false;    for (int j=0;j<=n-a;j++) {bool flag=true;    int max=0;        while (Flag&&!goal) {for (int k=0;k<a;k++) {pos[k]=find (map[k+j]+max,s[i][k],next);  if (pos[k]==-1) {flag=false;  Break      }} if (!flag) break;        max=0;        int count=0;            for (int k=0;k<a;k++) {if (pos[k]==pos[0]) count++;          Max=max (Max,pos[k]);          } if (count==a) {goal=true;          printf ("1\n");    }} if (goal) break;  } if (!goal) printf ("0\n"); }return 0;}

< method two >rabin-karp algorithm.

820112

Lizitong

2462

Accepted

2880 KB

980 Ms

C++/edit

3103 B

2014-12-27 11:35:21

#include <cstdio> #include <cstring> #include <algorithm>using namespace std;typedef unsigned long Long ull;const ull seed=31;ull seeds[1001];int N,m,a,b,q,pos[1001];char map[1001][1001],s[11][101][1001];// Brute force string comparison bool Strcmp (const char a[],const int &l1,const int &r1,const char b[],const int &l2,const int &r2) { for (int i=l1,j=l2;i<r1;++i,++j) if (A[i]!=b[j]) return 0;return 1;}  Natural overflow, L first pointer, R tail pointer, left closed right open ull bkdrhash (const char str[],const int &l,const int &r) {ull res=0;for (int i=l;i<r;++i) Res=res*seed+str[i];return Res;} Preprocessing to facilitate the transfer of hash (S[i...i+m-1] and hash (s[i+1...i+m]) void Init_seeds () {seeds[0]=1;for (int i=1;i<1001;++i) seeds[i] =seeds[i-1]*seed;} Text string lookup, s text string, sub substring int rabinkarp (const char s[],const char sub[]) {int N=strlen (s), M=strlen (sub), Ull hsub=bkdrhash (Sub,    0,M), Hs=bkdrhash (S,0,m), for (int i=0;i<=n-m;++i) {if (hs==hsub && Strcmp (s,i,i+m,sub,0,m)) return i; Hs= (Hs-s[i]*seeds[m-1]) *seed+s[i+m];//o (1) transfer}return-1;} Int Main () {init_seeds ();    scanf ("%d%d%d%d", &n,&m,&a,&b);    for (int i=0;i<n;i++) scanf ("%s", Map[i]);    scanf ("%d", &q);    for (int i=1;i<=q;i++) for (int j=0;j<a;j++) scanf ("%s", S[i][j]);            if (a==1) {for (int i=1;i<=q;i++) {bool Flag=false;                  for (int j=0;j<n;j++) if (Rabinkarp (map[j],s[i][0])!=-1) {flag=true;                  printf ("1\n");                Break          } if (!flag) printf ("0\n");      } return 0;        } for (int i=1;i<=q;i++) {bool Goal=false;            for (int j=0;j<=n-a;j++) {bool flag=true;            int max=0; while (Flag&&!goal) {for (int k=0;k<a;k++) {pos                    [K]=rabinkarp (Map[k+j]+max,s[i][k]);               if (pos[k]==-1) {         Flag=false;                      Break                }} if (!flag) break;                max=0;                int count=0;                    for (int k=0;k<a;k++) {if (pos[k]==pos[0]) count++;                  Max=max (Max,pos[k]);                    } if (count==a) {goal=true;                  printf ("1\n");          }} if (goal) break;      } if (!goal) printf ("0\n"); } return 0;}

Although the asymptotic complexity is the same, it is clear that KMP is more stable.

"KMP algorithm" "Rabin-karp algorithm" [BeiJing2011] Matrix template