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63 lines
1.4 KiB
C++
63 lines
1.4 KiB
C++
/*
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* C++ Program to Implement Rabin-Karp Algorithm
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*/
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#include <iostream>
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#include <cstdio>
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#include <cstring>
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#include <cstdlib>
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using namespace std;
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#define d 256
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/*
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* search a substring in a string
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*/
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void search(char *pat, char *txt, int q)
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{
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int M = strlen(pat);
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int N = strlen(txt);
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int i, j;
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int p = 0;
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int t = 0;
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int h = 1;
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for (i = 0; i < M - 1; i++)
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h = (h * d) % q;
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for (i = 0; i < M; i++)
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{
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p = (d *p + pat[i]) % q;
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t = (d * t + txt[i]) % q;
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}
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for (i = 0; i <= N - M; i++)
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{
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if (p == t)
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{
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for (j = 0; j < M; j++)
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{
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if (txt[i + j] != pat[j])
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break;
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}
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if (j == M)
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{
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cout<<"Pattern found at index: "<<i<<endl;
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}
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}
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if (i < N - M)
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{
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t = (d * (t - txt[i] * h) + txt[i + M]) % q;
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if (t < 0)
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t = (t + q);
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}
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}
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}
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/* Main */
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int main()
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{
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char *txt = "Sanfoundry Linux Training";
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char *pat = "nux";
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int q = 101;
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search(pat, txt, q);
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return 0;
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}
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/*
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Pattern found at index: 13
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