76 lines
2.3 KiB
C++
76 lines
2.3 KiB
C++
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template <int N, typename DataT = int>
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struct binary_trie {
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vector<tuple<array<int, 2>, DataT, array<int, 2>>> tr;
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binary_trie() : tr(1) {}
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void emplace(ll x, const DataT& data = {}) {
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int ptr = 0;
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for (int i = N - 1; ~i; --i) {
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int bit = x >> i & 1;
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if (not std::get<0>(tr[ptr])[bit]) {
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std::get<0>(tr[ptr])[bit] = tr.size();
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tr.emplace_back();
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}
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std::get<2>(tr[ptr])[bit] += 1;
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ptr = std::get<0>(tr[ptr])[bit];
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}
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std::get<1>(tr[ptr]) = data;
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}
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/// WARN: Don't try to erase a non-existent element!
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void erase(ll x) {
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int ptr = 0;
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vector<pii> st;
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for (int i = N - 1; ~i; --i) {
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int bit = x >> i & 1;
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st.emplace_back(ptr, bit);
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ptr = std::get<0>(tr[ptr])[bit];
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}
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while (st.size() and std::get<2>(tr[st.back().first])[st.back().second] == 1) {
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std::get<0>(tr[st.back().first])[st.back().second] = 0;
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std::get<2>(tr[st.back().first])[st.back().second] = 0;
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st.pop_back();
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}
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tr[ptr] = {};
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}
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optional<DataT> get(ll x) {
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int ptr = 0;
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for (int i = N - 1; ~i; --i) {
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int bit = x >> i & 1;
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if (not std::get<0>(tr[ptr])[bit]) return {};
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ptr = std::get<0>(tr[ptr])[bit];
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}
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return { std::get<1>(tr[ptr]) };
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}
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int count_prefix(ll x, int bits = N) {
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int ptr = 0;
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int res = 0;
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for (int i = N - 1; i > max(-1, N - 1 - bits); --i) {
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int bit = x >> 1 & 1;
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if (not std::get<0>(tr[ptr])[bit]) return 0;
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ptr = std::get<0>(tr[ptr])[bit];
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res = std::get<2>(tr[ptr])[bit];
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}
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return res;
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}
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optional<pair<ll, DataT&>> get_max_xor(ll x) {
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int ptr = 0;
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ll res = 0;
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for (int i = N - 1; ~i; --i) {
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int bit = x >> i & 1;
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if (std::get<0>(tr[ptr])[1 ^ bit]) {
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ptr = std::get<0>(tr[ptr])[1 ^ bit];
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res |= (1 ^ bit) << i;
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} else if (std::get<0>(tr[ptr])[bit]) {
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ptr = std::get<0>(tr[ptr])[bit];
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res |= bit << i;
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} else {
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return {};
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}
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}
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return {{ res, std::get<1>(tr[ptr]) }};
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}
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};
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