Create fenwick_tree.cpp

Changes

1 changed files (+11/-0)

• Data Structures/fenwick_tree.cpp (new)
  • @@ -0,0 +1,11 @@
    + #include <vector> + using namespace std; + + class fenwick_tree { + private: vector<int> FT; + public: + fenwick_tree(int N) { FT.assign(N + 1, 0); } + void update(int x, int val) { for (; x < FT.size(); x += x & -x) FT[x] += val; } + int query(int x) { int ret = 0; for (; x > 0; x -= x & -x) ret += FT[x]; return ret; } + int query(int x, int y) { return query(y) - (x == 1 ? 0 : query(x - 1)); } + };