提出 #7547348

---

ソースコード 拡げる

#pragma GCC optimize ("Ofast")
#include<bits/stdc++.h>
using namespace std;
void *wmem;
char memarr[96000000];
template<class T> inline void walloc1d(T **arr, int x, void **mem = &wmem){
  static int skip[16] = {0, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1};
  (*mem) = (void*)( ((char*)(*mem)) + skip[((unsigned long long)(*mem)) & 15] );
  (*arr)=(T*)(*mem);
  (*mem)=((*arr)+x);
}
inline void rd(int &x){
  int k;
  int m=0;
  x=0;
  for(;;){
    k = getchar_unlocked();
    if(k=='-'){
      m=1;
      break;
    }
    if('0'<=k&&k<='9'){
      x=k-'0';
      break;
    }
  }
  for(;;){
    k = getchar_unlocked();
    if(k<'0'||k>'9'){
      break;
    }
    x=x*10+k-'0';
  }
  if(m){
    x=-x;
  }
}
inline void rd(char &c){
  int i;
  for(;;){
    i = getchar_unlocked();
    if(i!=' '&&i!='\n'&&i!='\r'&&i!='\t'&&i!=EOF){
      break;
    }
  }
  c = i;
}
inline int rd(char c[]){
  int i;
  int sz = 0;
  for(;;){
    i = getchar_unlocked();
    if(i!=' '&&i!='\n'&&i!='\r'&&i!='\t'&&i!=EOF){
      break;
    }
  }
  c[sz++] = i;
  for(;;){
    i = getchar_unlocked();
    if(i==' '||i=='\n'||i=='\r'||i=='\t'||i==EOF){
      break;
    }
    c[sz++] = i;
  }
  c[sz]='\0';
  return sz;
}
inline void wt_L(char a){
  putchar_unlocked(a);
}
inline void wt_L(int x){
  int s=0;
  int m=0;
  char f[10];
  if(x<0){
    m=1;
    x=-x;
  }
  while(x){
    f[s++]=x%10;
    x/=10;
  }
  if(!s){
    f[s++]=0;
  }
  if(m){
    putchar_unlocked('-');
  }
  while(s--){
    putchar_unlocked(f[s]+'0');
  }
}
template<class S, class T> inline S chmin(S &a, T b){
  if(a>b){
    a=b;
  }
  return a;
}
template<class S, class T> inline S chmax(S &a, T b){
  if(a<b){
    a=b;
  }
  return a;
}
template<class T> void SuffixArray(T *s, int N, int K, int *SA, int *LCP = NULL, void *mem = wmem){
  int i;
  int j;
  int d;
  int m;
  int *s1;
  int name;
  int prev;
  int pos;
  char *t;
  char *lms;
  int *cnt;
  int *cnt1;
  int *cnt2;
  walloc1d(&t, N+1, &mem);
  walloc1d(&lms, N+1, &mem);
  walloc1d(&cnt, K+1, &mem);
  walloc1d(&cnt1, K+1, &mem);
  walloc1d(&cnt2, K+1, &mem);
  N++;
  s[N-1] = 0;
  t[N-1] = 1;
  t[N-2] = 0;
  for(i=N-3;i>=0;i--){
    if(s[i] < s[i+1] || (s[i]==s[i+1] && t[i+1])){
      t[i] = 1;
    }
    else{
      t[i] = 0;
    }
  }
  lms[0] = 0;
  for(i=(1);i<(N);i++){
    if(t[i] && !t[i-1]){
      lms[i] = 1;
    }
    else{
      lms[i] = 0;
    }
  }
  for(i=0;i<(K+1);i++){
    cnt1[i] = 0;
  }
  for(i=0;i<(N);i++){
    cnt1[s[i]]++;
  }
  j = 0;
  for(i=0;i<(K+1);i++){
    j += cnt1[i];
    cnt2[i] = j - cnt1[i];
    cnt1[i] = j;
  }
  for(i=0;i<(K+1);i++){
    cnt[i] = cnt1[i];
  }
  for(i=0; i<N; i++){
    SA[i] = -1;
  }
  for(i=1; i<N; i++){
    if(lms[i]){
      SA[--cnt[s[i]]]=i;
    }
  }
  for(i=0;i<(K+1);i++){
    cnt[i] = cnt2[i];
  }
  for(i=0;i<(N);i++){
    j = SA[i]-1;
    if(j>=0 && !t[j]){
      SA[cnt[s[j]]++] = j;
    }
  }
  for(i=0;i<(K+1);i++){
    cnt[i] = cnt1[i];
  }
  for(i=N-1;i>=0;i--){
    j = SA[i] - 1;
    if(j>=0 && t[j]){
      SA[--cnt[s[j]]] = j;
    }
  }
  m = 0;
  for(i=0;i<(N);i++){
    if(lms[SA[i]]){
      SA[m++] = SA[i];
    }
  }
  for(i=(m);i<(N);i++){
    SA[i] = -1;
  }
  name=0;
  prev=-1;
  for(i=0;i<(m);i++){
    pos = SA[i];
    for(d=0;d<(N);d++){
      if(prev==-1 || s[pos+d]!=s[prev+d] || t[pos+d]!=t[prev+d]){
        name++;
        prev=pos;
        break;
      }
      else if(d>0 && (lms[pos+d] || lms[prev+d])){
        break;
      }
    }
    pos /= 2;
    SA[m+pos]=name-1;
  }
  for(i=N-1, j=N-1; i>=m; i--){
    if(SA[i]>=0){
      SA[j--]=SA[i];
    }
  }
  s1 = SA+N-m;
  if(name<m){
    SuffixArray(s1, m-1, name-1, SA, NULL, mem);
  }
  else{
    for(i=0; i<m; i++){
      SA[s1[i]] = i;
    }
  }
  for(i=0;i<(K+1);i++){
    cnt[i] = cnt1[i];
  }
  for(i=1, j=0; i<N; i++){
    if(lms[i]){
      s1[j++]=i;
    }
  }
  for(i=0; i<m; i++){
    SA[i]=s1[SA[i]];
  }
  for(i=m; i<N; i++){
    SA[i]=-1;
  }
  for(i=m-1; i>=0; i--){
    j=SA[i];
    SA[i]=-1;
    SA[--cnt[s[j]]]=j;
  }
  for(i=0;i<(N);i++){
    j = SA[i]-1;
    if(j>=0 && !t[j]){
      SA[cnt2[s[j]]++] = j;
    }
  }
  for(i=N-1;i>=0;i--){
    j = SA[i] - 1;
    if(j>=0 && t[j]){
      SA[--cnt1[s[j]]] = j;
    }
  }
  if(LCP != NULL){
    cnt = (int*)t;
    d = 0;
    for(i=0;i<(N);i++){
      cnt[SA[i]] = i;
    }
    for(i=0;i<(N);i++){
      if(cnt[i]){
        for(j=SA[cnt[i]-1]; j+d<N-1&&i+d<N-1&&s[j+d]==s[i+d];d++){
          ;
        }
        LCP[cnt[i]]=d;
      }
      else{
        LCP[cnt[i]] = -1;
      }
      if(d>0){
        d--;
      }
    }
  }
}
int N;
char S[5002];
int SA[5002];
int LCP[5002];
int main(){
  wmem = memarr;
  int i;
  int j;
  int ok;
  int mn;
  int mx;
  int res = 0;
  rd(N);
  rd(S);
  SuffixArray(S, N, 128, SA, LCP);
  int Lj4PdHRW;
  int KL2GvlyY;
  int Q5VJL1cS;
  Lj4PdHRW = 0;
  KL2GvlyY = N/2;
  while(Lj4PdHRW < KL2GvlyY){
    if((Lj4PdHRW + KL2GvlyY)%2==0){
      Q5VJL1cS = (Lj4PdHRW + KL2GvlyY) / 2;
    }
    else{
      Q5VJL1cS = (Lj4PdHRW + KL2GvlyY + 1) / 2;
    }
    ok = 0;
    i = 1;
    while(i < N+1){
      j = i;
      mn = mx = SA[i];
      while(j+1 < N+1 && LCP[j+1] >= Q5VJL1cS){
        j++;
        chmin(mn, SA[j]);
        chmax(mx, SA[j]);
      }
      if(mx - mn >= Q5VJL1cS){
        ok = 1;
        break;
      }
      i = j + 1;
    }
    if(ok){
      Lj4PdHRW = Q5VJL1cS;
    }
    else{
      KL2GvlyY = Q5VJL1cS - 1;
    }
  }
  res =KL2GvlyY;
  wt_L(res);
  wt_L('\n');
  return 0;
}
// cLay varsion 20190914-1

// --- original code ---
// int N;
// char S[5002];
// 
// int SA[5002], LCP[5002];
// {
//   int i, j, ok, mn, mx;
//   int res = 0;
//   rd(N,S);
//   SuffixArray(S, N, 128, SA, LCP);
//   res = bsearch_max[int,x,0,N/2][
//     ok = 0;
//     i = 1;
//     while(i < N+1){
//       j = i;
//       mn = mx = SA[i];
//       while(j+1 < N+1 && LCP[j+1] >= x){
//         j++;
//         mn <?= SA[j];
//         mx >?= SA[j];
//       }
//       if(mx - mn >= x) ok = 1, break;
//       i = j + 1;
//     }
//   ](ok);
//   wt(res);
// }

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