31 lines
571 B
C++
31 lines
571 B
C++
int kmp(string & S, string & T) {
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// Generate KMP table
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vector<int> F(T.size()+1, 0);
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F[0] = -1;
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for (int i = 0; i < T.size(); ++i) {
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F[i+1] = F[i];
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while (F[i+1] > -1 && T[i] != T[F[i+1]]) F[i+1] = F[F[i+1]];
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++F[i+1];
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}
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// Search
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int i = 0, j = 0;
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while (i < S.size()) {
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if (S[i] == T[j]) {
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++i, ++j;
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if (j == T.size()) return i - j; // Found match
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/*if (j == T.size()) {
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++ret; // Count matches
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j = F[j];
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if (j < 0) ++i, ++j;
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}*/
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}
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else {
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j = F[j];
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if (j < 0) ++i, ++j;
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}
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}
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return -1; // Match not found
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}
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