POJ 3882 (stammering aliens) suffix array or hash

Suffix array: Construct a suffix array, and note that you want to add a character that does not appear at the end of the string. Then it can be 2 points or direct scan, the direct scan needs to use the monotone queue to maintain

VIEW CODE

#include <cstdio> #include <algorithm> #include <iostream> #include <cmath> #include <queue > #include <stack> #include <string> #include <cstring> #include <map> #include <vector > #include <set> #include <ctime> #include <stdlib.h>using namespace Std;const int mmax= 40010;const int mod=1000000007;typedef Long Long ll;//typedef unsigned long long ull;char s[mmax];int sa[mmax],t[mmax],t2[mmax],c[    Mmax],n;void build_sa (int m) {int i,*x=t,*y=t2;    for (i=0;i<m;i++) c[i]=0;    for (i=0;i<n;i++) c[x[i]=s[i]]++;    for (i=1;i<m;i++) c[i]+=c[i-1];    for (i=n-1;i>=0;i--) sa[--c[x[i]]]=i;        for (int k=1;k<=n;k<<=1) {int p=0;        for (i=n-k;i<n;i++) y[p++]=i;        for (i=0;i<n;i++) if (sa[i]>=k) y[p++]=sa[i]-k;        for (i=0;i<m;i++) c[i]=0;        for (i=0;i<n;i++) c[x[y[i]]]++;        for (i=1;i<m;i++) c[i]+=c[i-1];        for (i=n-1;i>=0;i--) sa[--c[x[y[i]]]]=y[i];      Swap (x, y);  p=1;x[sa[0]]=0;        for (i=1;i<n;i++) x[sa[i]] = Y[sa[i-1]]==y[sa[i]] && y[sa[i-1]+k]==y[sa[i]+k]?p-1:p++;        if (p>=n) break;    M=p;    }}int rank[mmax],heigth[mmax];void Getheigth () {for (int i=0;i<n;i++) rank[sa[i]]=i;    int k=0;        for (int i=0;i<n;i++) {if (k) k--;            if (Rank[i]) {int j=sa[rank[i]-1];            while (S[i+k]==s[j+k]) k++;        Heigth[rank[i]]=k;    }}}int len[mmax];int mark[mmax];int head,end,head1,end1;int main () {int m;        while (scanf ("%d", &m) &&m) {head=end=0;        head1=end1=0;        scanf ("%s", s);            if (m==1) {printf ("%d%d\n", strlen (s), 0);        Continue        } n=strlen (s);        S[n++]= ' $ ';        s[n]=0;        BUILD_SA (131);        Getheigth ();                for (int i=1;i<m;i++) {while (End>head && heigth[len[end-1]]>= heigth[i])            end--; LeN[end++]=i;            while (End1>head1 && Sa[mark[end1-1]] <sa[i]) end1--;        Mark[end1++]=i;        } int Ans=heigth[len[head]];        int E=sa[mark[head1]];            for (int i=m;i<n;i++) {if (I-m+1==len[head]) head++;            while (End>head && heigth[len[end-1]]>= heigth[i]) end--;            Len[end++]=i;            if (I-m==mark[head1]) head1++;            while (End1>head1 && Sa[mark[end1-1]] <sa[i]) end1--;            Mark[end1++]=i;                if (Heigth[len[head]]>ans) {Ans=heigth[len[head]];            E=SA[MARK[HEAD1]];        } else if (Heigth[len[head]]==ans) E=max (E,sa[mark[head1]]);            } if (ans==0) {puts ("none");        Continue    } printf ("%d%d\n", ans,e); } return 0;}

String hash: Direct 2 points well written.

VIEW CODE

#include <cstdio> #include <algorithm> #include <iostream> #include <cmath> #include <queue > #include <stack> #include <string> #include <cstring> #include <map> #include <vector > #include <set> #include <ctime> #include <stdlib.h>using namespace std;const int mmax= 1000010; const int Mod=1000000007;const int inf=0x3fffffff;using namespace std;typedef long long ll;typedef unsigned long long ULL ; ULL h[mmax];map<ull,int>q;int M;char Str[mmax];    ULL pow[mmax];void Build_ha () {int n=strlen (str);    h[n]=0; for (int i=n-1;i>=0;i--) h[i]=h[i+1]*131+str[i];}    ULL ha[mmax];bool ok (int k) {int n=strlen (str);        for (int i=0;i+k-1<n;i++) {ULL tmp=h[i]-h[i+k]*pow[k];    ha[i]=tmp;    } sort (ha,ha+n-k+1);    int cnt=0;        for (int i=0;i<n-k+1;i++) {if (I && ha[i]==ha[i-1]) cnt++;            else {if (cnt>=m) return 1;        Cnt=1;}} if (cnt>=m) return 1; return 0;}    int main () {pow[0]=1;    for (int i=1;i<mmax;i++) pow[i]=pow[i-1]*131;        while (cin>>m&&m) {scanf ("%s", str);        int N=strlen (str);        int l=1,r=n+1;        Build_ha ();            while (l<r) {int mid= (L+R) >>1;            if (OK (mid)) l=mid+1;        else R=mid;        } int ans=r-1;            if (!ans) {puts ("none");        Continue        } int e;        Q.clear ();            for (int i=0;i+ans-1<n;i++) {ULL Tmp=h[i]-h[i+ans]*pow[ans];            q[tmp]++;        if (q[tmp]>=m) e=i;    } printf ("%d%d\n", ans,e); } return 0;}

POJ 3882 (stammering aliens) suffix array or hash