implementation of KMP algorithm

Implementation_of_KMP_algorithm.cpp

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+#include <iostream>
+using namespace std;
+
+// Function to implement the KMP algorithm
+void KMP(string X, string Y)
+{
+    int m = X.length();
+    int n = Y.length();
+
+    // if `Y` is an empty string
+    if (n == 0)
+    {
+        cout << "The pattern occurs with shift 0";
+        return;
+    }
+
+    // if X's length is less than that of Y'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 && Y[j] != Y[i]) {
+            j = next[j];
+        }
+
+        if (j > 0 || Y[j] == Y[i]) {
+            next[i + 1] = j + 1;
+        }
+    }
+
+    for (int i = 0, j = 0; i < m; i++)
+    {
+        if (X[i] == Y[j])
+        {
+            if (++j == n) {
+                cout << "The pattern occurs with shift " << i - j + 1 << endl;
+            }
+        }
+        else if (j > 0)
+        {
+            j = next[j];
+            i--;    // since `i` will be incremented in the next iteration
+        }
+    }
+}
+
+// Program to implement the KMP algorithm in C++
+int main()
+{
+    string text = "ABCABAABCABAC";
+    string pattern = "CAB";
+
+    KMP(text, pattern);
+
+    return 0;
+}