Update fenwick_tree.cpp

Changes

1 changed files (+7/-6)

• Data Structures/fenwick_tree.cpp
  • @@ -1,8 +1,9 @@
    template<typename T> class fenwick_tree { - private: vector<T> FT; + private: int N; T FT[MX]; public: - fenwick_tree(int N) { FT.assign(N + 5, 0); } - void update(int x, T val) { if (++x) for (; x < FT.size(); x += x & -x) FT[x] += val; } - T query(int x) { T ret = 0; if (++x) for (; x; x -= x & -x) ret += FT[x]; return ret; } - T query(int x, int y) { return query(y) - query(x - 1); } - }; + fenwick_tree(int n) { N = n } + fenwick_tree(int n, T A[]) { N = n; memcpy(FT, A, sizeof FT); } + void update(int x, T val) { if (++x) for (; x < N; x += x&-x) FT[x] += val; } + T query(int x) { T ret = 0; if (++x) for (; x; x -= x&-x) ret += FT[x]; return ret; } + T query(int x, int y) { return query(y)-query(x-1); } + };