Create Implement_KMP_Algorithm.cpp for Pattern Searching

Implement_KMP_Algorithm.cpp for Pattern Searching

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+#include <iostream>
+using namespace std;
+
+// Function to implement the KMP algorithm
+void KMP(string text, string pattern)
+{
+ int m = text.length();
+ int n = pattern.length();
+
+ // if pattern is an empty string
+ if (n == 0)
+ {
+ cout << "The pattern occurs with shift 0";
+ return;
+ }
+
+ // if text's length is less than that of pattern's
+ if (m < n)
+ {
+ cout << "Pattern not found";
+ return;
+ }
+
+ // next[i] stores the index of the next best partial match
+ int next[n + 1];
+
+ for (int i = 0; i < n + 1; i++) {
+ next[i] = 0;
+ }
+
+ for (int i = 1; i < n; i++)
+ {
+ int j = next[i + 1];
+
+ while (j > 0 && pattern[j] != pattern[i]) {
+ j = next[j];
+ }
+
+ if (j > 0 || pattern[j] == pattern[i]) {
+ next[i + 1] = j + 1;
+ }
+ }
+
+ for (int i = 0, j = 0; i < m; i++)
+ {
+ if (text[i] == pattern[j])
+ {
+ if (++j == n) {
+ cout << "The pattern occurs with shift " << i - j + 1 << endl;
+ }
+ }
+ else if (j > 0)
+ {
+ j = next[j];
+ i--; 
+ }
+ }
+}
+
+int main()
+{
+ string text = "ABCABAABCABAC";
+ string pattern = "CAB";
+
+ KMP(text, pattern);
+
+ return 0;
+}