24 lines
650 B
C++
24 lines
650 B
C++
template<typename T> class fenwick_tree_2d {
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private: int N, M; vector<vector<T>> FT;
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public:
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fenwick_tree_2d(int n, int m) {
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N = n + 1, M = m + 1;
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FT.resize(N);
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for (int i = 0; i < N; i++) FT[i].resize(M, 0);
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}
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void update(int x, int y, T val) {
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for (int i = x; i < N; i += i & -i) {
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for (int j = y; j < M; j += j & -j) FT[i][j] += val;
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}
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}
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T query(int x, int y) {
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T ret = 0;
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for (int i = x; i > 0; i -= i & -i) {
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for (int j = y; j > 0; j -= j & -j) ret += FT[i][j];
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}
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return ret;
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}
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T query(int xl, int xr, int yl, int yr) {
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return query(xr, yr) - query(xl - 1, yr) - query(xr, yl - 1) + query(xl - 1, yl - 1);
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}
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}; |