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Add trees/binary_trie.cc 

Signed-off-by: subcrip <contact@subc.rip>
This commit is contained in:
subcrip 2024-06-04 23:22:06 +08:00
parent 4b5dd8da79
commit 5c24ca38ad
1 changed files with 75 additions and 0 deletions
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trees/binary_trie.cc Normal file
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template <int N, typename DataT = int>
struct binary_trie {
vector<tuple<array<int, 2>, DataT, array<int, 2>>> tr;
binary_trie() : tr(1) {}
void emplace(ll x, const DataT& data = {}) {
int ptr = 0;
for (int i = N - 1; ~i; --i) {
int bit = x >> i & 1;
if (not std::get<0>(tr[ptr])[bit]) {
std::get<0>(tr[ptr])[bit] = tr.size();
tr.emplace_back();
}
std::get<2>(tr[ptr])[bit] += 1;
ptr = std::get<0>(tr[ptr])[bit];
}
std::get<1>(tr[ptr]) = data;
}
/// WARN: Don't try to erase a non-existent element!
void erase(ll x) {
int ptr = 0;
vector<pii> st;
for (int i = N - 1; ~i; --i) {
int bit = x >> i & 1;
st.emplace_back(ptr, bit);
ptr = std::get<0>(tr[ptr])[bit];
}
while (st.size() and std::get<2>(tr[st.back().first])[st.back().second] == 1) {
std::get<0>(tr[st.back().first])[st.back().second] = 0;
std::get<2>(tr[st.back().first])[st.back().second] = 0;
st.pop_back();
}
tr[ptr] = {};
}
optional<DataT> get(ll x) {
int ptr = 0;
for (int i = N - 1; ~i; --i) {
int bit = x >> i & 1;
if (not std::get<0>(tr[ptr])[bit]) return {};
ptr = std::get<0>(tr[ptr])[bit];
}
return { std::get<1>(tr[ptr]) };
}
int count_prefix(ll x, int bits = N) {
int ptr = 0;
int res = 0;
for (int i = N - 1; i > max(-1, N - 1 - bits); --i) {
int bit = x >> 1 & 1;
if (not std::get<0>(tr[ptr])[bit]) return 0;
ptr = std::get<0>(tr[ptr])[bit];
res = std::get<2>(tr[ptr])[bit];
}
return res;
}
optional<pair<ll, DataT&>> get_max_xor(ll x) {
int ptr = 0;
ll res = 0;
for (int i = N - 1; ~i; --i) {
int bit = x >> i & 1;
if (std::get<0>(tr[ptr])[1 ^ bit]) {
ptr = std::get<0>(tr[ptr])[1 ^ bit];
res |= (1 ^ bit) << i;
} else if (std::get<0>(tr[ptr])[bit]) {
ptr = std::get<0>(tr[ptr])[bit];
res |= bit << i;
} else {
return {};
}
}
return {{ res, std::get<1>(tr[ptr]) }};
}
};