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Add string/slice_hash.cc

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subcrip 2024-04-10 13:53:42 +08:00
parent 3c19859012
commit 0018dbf69f
1 changed files with 23 additions and 0 deletions
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string/slice_hash.cc Normal file
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struct slice_hash {
using hash_type = pair<MLL<MDL1>, MLL<MDL2>>;
int n;
vector<MLL<MDL1>> pw1;
vector<MLL<MDL2>> pw2;
vector<MLL<MDL1>> hash1;
vector<MLL<MDL2>> hash2;
slice_hash(const string& s) : n(s.size()), pw1(n + 1), pw2(n + 1), hash1(n + 1), hash2(n + 1) {
constexpr int b = 31;
pw1[0] = 1, pw2[0] = 1;
for (int i = 1; i <= n; ++i) {
hash1[i] = hash1[i - 1] + s[i - 1] * pw1[i - 1];
hash2[i] = hash2[i - 1] + s[i - 1] * pw2[i - 1];
pw1[i] = pw1[i - 1] * b;
pw2[i] = pw2[i - 1] * b;
}
}
// query [l, r]
hash_type hash(int l, int r) {
return { (hash1[r + 1] - hash1[l]) / pw1[l], (hash2[r + 1] - hash2[l]) / pw2[l] };
}
};