string/suffix_array.hpp

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• Last update: 2024-03-09 20:36:28+09:00
• Include: #include "string/suffix_array.hpp"

Verified with

• test/suffix_array.test.cpp

Code

#pragma once

#include <bits/stdc++.h> 
using namespace std;



struct SuffixArray {
  vector< int > SA;
  const string s;

  SuffixArray(const string &str) : s(str) {
    SA.resize(s.size());
    iota(begin(SA), end(SA), 0);
    sort(begin(SA), end(SA), [&](int a, int b) {
      return s[a] == s[b] ? a > b : s[a] < s[b];
    });
    vector< int > classes(s.size()), c(s.begin(), s.end()), cnt(s.size());
    for(int len = 1; len < s.size(); len <<= 1) {
      for(int i = 0; i < s.size(); i++) {
        if(i > 0 && c[SA[i - 1]] == c[SA[i]] && SA[i - 1] + len < s.size() && c[SA[i - 1] + len / 2] == c[SA[i] + len / 2]) {
          classes[SA[i]] = classes[SA[i - 1]];
        } else {
          classes[SA[i]] = i;
        }
      }
      iota(begin(cnt), end(cnt), 0);
      copy(begin(SA), end(SA), begin(c));
      for(int i = 0; i < s.size(); i++) {
        int s1 = c[i] - len;
        if(s1 >= 0) SA[cnt[classes[s1]]++] = s1;
      }
      classes.swap(c);
    }
  }

  int operator[](int k) const {
    return SA[k];
  }

  size_t size() const {
    return s.size();
  }

  bool lt_substr(const string &t, int si = 0, int ti = 0) {
    int sn = (int) s.size(), tn = (int) t.size();
    while(si < sn && ti < tn) {
      if(s[si] < t[ti]) return true;
      if(s[si] > t[ti]) return false;
      ++si, ++ti;
    }
    return si >= sn && ti < tn;
  }

  int lower_bound(const string &t) {
    int low = -1, high = (int) SA.size();
    while(high - low > 1) {
      int mid = (low + high) / 2;
      if(lt_substr(t, SA[mid])) low = mid;
      else high = mid;
    }
    return high;
  }

  pair< int, int > lower_upper_bound(string &t) {
    int idx = lower_bound(t);
    int low = idx - 1, high = (int) SA.size();
    t.back()++;
    while(high - low > 1) {
      int mid = (low + high) / 2;
      if(lt_substr(t, SA[mid])) low = mid;
      else high = mid;
    }
    t.back()--;
    return {idx, high};
  }

  void output() {
    for(int i = 0; i < size(); i++) {
      cout << i << ": " << s.substr(SA[i]) << endl;
    }
  }
};

#line 2 "string/suffix_array.hpp"

#include <bits/stdc++.h> 
using namespace std;



struct SuffixArray {
  vector< int > SA;
  const string s;

  SuffixArray(const string &str) : s(str) {
    SA.resize(s.size());
    iota(begin(SA), end(SA), 0);
    sort(begin(SA), end(SA), [&](int a, int b) {
      return s[a] == s[b] ? a > b : s[a] < s[b];
    });
    vector< int > classes(s.size()), c(s.begin(), s.end()), cnt(s.size());
    for(int len = 1; len < s.size(); len <<= 1) {
      for(int i = 0; i < s.size(); i++) {
        if(i > 0 && c[SA[i - 1]] == c[SA[i]] && SA[i - 1] + len < s.size() && c[SA[i - 1] + len / 2] == c[SA[i] + len / 2]) {
          classes[SA[i]] = classes[SA[i - 1]];
        } else {
          classes[SA[i]] = i;
        }
      }
      iota(begin(cnt), end(cnt), 0);
      copy(begin(SA), end(SA), begin(c));
      for(int i = 0; i < s.size(); i++) {
        int s1 = c[i] - len;
        if(s1 >= 0) SA[cnt[classes[s1]]++] = s1;
      }
      classes.swap(c);
    }
  }

  int operator[](int k) const {
    return SA[k];
  }

  size_t size() const {
    return s.size();
  }

  bool lt_substr(const string &t, int si = 0, int ti = 0) {
    int sn = (int) s.size(), tn = (int) t.size();
    while(si < sn && ti < tn) {
      if(s[si] < t[ti]) return true;
      if(s[si] > t[ti]) return false;
      ++si, ++ti;
    }
    return si >= sn && ti < tn;
  }

  int lower_bound(const string &t) {
    int low = -1, high = (int) SA.size();
    while(high - low > 1) {
      int mid = (low + high) / 2;
      if(lt_substr(t, SA[mid])) low = mid;
      else high = mid;
    }
    return high;
  }

  pair< int, int > lower_upper_bound(string &t) {
    int idx = lower_bound(t);
    int low = idx - 1, high = (int) SA.size();
    t.back()++;
    while(high - low > 1) {
      int mid = (low + high) / 2;
      if(lt_substr(t, SA[mid])) low = mid;
      else high = mid;
    }
    t.back()--;
    return {idx, high};
  }

  void output() {
    for(int i = 0; i < size(); i++) {
      cout << i << ": " << s.substr(SA[i]) << endl;
    }
  }
};

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