【封装工程】OI/ACM常用封装

【ST表（静态RMQ）】

// program at 2019-11-12
template <class T, int N, int M>
struct ST {
  T f[N + 5][M + 1];
  int log2[N];
  T compare(T x, T y) {
    return x < y ? x : y; 
  }
  void init(int* a) {
    log2[0] = -1;
    for (int i = 1; i <= N; i++)
      f[i][0] = a[i], log2[i] = log2[i >> 1] + 1;
    for (int j = 1; j <= M; j++)
      for (int i = 1; i + (1 << j) - 1 <= N; i++)
        f[i][j] = compare(f[i][j - 1], f[i + (1 << (j - 1))][j - 1]);
  }
  T query(int l, int r) {
    int k = log2[r - l + 1];
    return compare(f[l][k], f[r - (1 << k) + 1][k]);
  }
};

来源：https://www.cnblogs.com/chhokmah/p/11844955.html