SuffixArray simple v2

struct SuffixArray {
  string s;
  int n;
  vector<int> arr;
  #define modulo(x) (x >= n ? x - n : x)
  SuffixArray(const string& str)
    : s(str + char(0))
    , n(size(s))
    , arr(n)
  {
    vector<int> c(n), buff(c);
    iota(all(arr), 0);
    for (int deg = 0; (1 << (deg - 1)) < n; deg++) {
      if (deg == 0) {
        sort(all(arr), [&] (int i, int j) { return s[i] < s[j]; });
        for (int i = 1; i < n; i++) {
          c[arr[i]] = c[arr[i - 1]] + (s[arr[i]] == s[arr[i - 1]] ? 0 : 1);
        }
      } else {
        int len = 1 << (deg - 1);
        for (int i = 1, j = 1; i < n; i = j) {
          while (j < n && c[arr[i]] == c[arr[j]]) j++;
          sort(begin(arr) + i, begin(arr) + j, [&] (int a, int b) {
            return c[modulo(a + len)] < c[modulo(b + len)];
          });
        }
        for (int i = 1; i < n; i++) {
          buff[arr[i]] = buff[arr[i - 1]];
          if (c[arr[i]] != c[arr[i - 1]] || c[modulo(arr[i] + len)] != c[modulo(arr[i - 1] + len)]) {
            buff[arr[i]]++;
          }
        }
        copy(all(buff), begin(c));
      }
    }
  }
  void Print() {
    for (int val : arr) {
      cout << val << ' ';
    }
    cout << '\n';
  }
  #undef modulo
};