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/*
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* C++ Program to Implement Knuth–Morris–Pratt Algorithm (KMP)
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*/
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#include <iostream>
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#include <cstring>
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using namespace std;
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void preKMP(string pattern, int f[])
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{
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int m = pattern.length(), k;
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f[0] = -1;
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for (int i = 1; i < m; i++)
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{
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k = f[i - 1];
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while (k >= 0)
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{
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if (pattern[k] == pattern[i - 1])
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break;
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else
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k = f[k];
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}
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f[i] = k + 1;
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}
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}
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//check whether target string contains pattern
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bool KMP(string pattern, string target)
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{
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int m = pattern.length();
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int n = target.length();
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int f[m];
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preKMP(pattern, f);
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int i = 0;
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int k = 0;
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while (i < n)
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{
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if (k == -1)
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{
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i++;
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k = 0;
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}
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else if (target[i] == pattern[k])
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{
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i++;
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k++;
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if (k == m)
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return 1;
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}
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else
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k = f[k];
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}
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return 0;
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}
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int main()
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{
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string tar = "san and linux training";
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string pat = "lin";
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if (KMP(pat, tar))
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cout<<"'"<<pat<<"' found in string '"<<tar<<"'"<<endl;
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else
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cout<<"'"<<pat<<"' not found in string '"<<tar<<"'"<<endl;
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pat = "sanfoundry";
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if (KMP(pat, tar))
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cout<<"'"<<pat<<"' found in string '"<<tar<<"'"<<endl;
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else
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cout<<"'"<<pat<<"' not found in string '"<<tar<<"'"<<endl;
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return 0;
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}
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/*
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'lin' found in string 'san and linux training'
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'sanfoundry' not found in string 'san and linux training'
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