cpp/data-structure/binary-indexed-tree.cpp

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• Last update: 2024-01-24 16:14:34+09:00

Required by

• cpp/geometry/two-points-distance.cpp
• cpp/math/meissel-lehhmer.cpp

Verified with

• cpp/z_test/yosupo-counting_primes.cpp

Code

template<typename T>
struct BIT{//1_Indexed
  int n;
  vector<T> bit;
  BIT(){}
  BIT(int n_):n(n_+1),bit(n,0){}

  void set(int n_){
    n = n_;
    bit.assign(n,0);
  }

  T sum(int a){
    T ret = 0;
    for(int i = a; i > 0; i -= i & -i) ret += bit[i];
    return ret;
  }

  void add(int a,T w){
    for(int i = a; i <= n; i += i & -i)bit[i] += w;
  }

  T query(int r,int l){
    return sum(l-1)-sum(r-1);
  }


  int lower_bound(T x){
    if(x <= 0){
      return 0;
    }
    x--;
    int t = 1;
    while(t < n)t <<= 1;
    int st = 0;
    int base = 0;
    for(; t; t/=2){
      if(st+t <= n && base+bit[st+t] <= x){
        base += bit[st+t];
        st += t;
      }
    }
    return st+1;
  }
};

#line 1 "cpp/data-structure/binary-indexed-tree.cpp"
template<typename T>
struct BIT{//1_Indexed
  int n;
  vector<T> bit;
  BIT(){}
  BIT(int n_):n(n_+1),bit(n,0){}

  void set(int n_){
    n = n_;
    bit.assign(n,0);
  }

  T sum(int a){
    T ret = 0;
    for(int i = a; i > 0; i -= i & -i) ret += bit[i];
    return ret;
  }

  void add(int a,T w){
    for(int i = a; i <= n; i += i & -i)bit[i] += w;
  }

  T query(int r,int l){
    return sum(l-1)-sum(r-1);
  }


  int lower_bound(T x){
    if(x <= 0){
      return 0;
    }
    x--;
    int t = 1;
    while(t < n)t <<= 1;
    int st = 0;
    int base = 0;
    for(; t; t/=2){
      if(st+t <= n && base+bit[st+t] <= x){
        base += bit[st+t];
        st += t;
      }
    }
    return st+1;
  }
};

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