8 lines
366 B
C++
8 lines
366 B
C++
template<typename T> class fenwick_tree {
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private: vector<T> FT;
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public:
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fenwick_tree(int N) { FT.assign(N + 1, 0); }
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void update(int x, T val) { if (x > 0) for (; x < FT.size(); x += x & -x) FT[x] += val; }
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T query(int x) { T ret = 0; if (x > 0) for (; x > 0; x -= x & -x) ret += FT[x]; return ret; }
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T query(int x, int y) { return query(y) - query(x - 1); }
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}; |