Change project structure to a Maven Java project + Refactor (#2816)

src/main/java/com/thealgorithms/others/KMP.java

@@ -0,0 +1,57 @@
+package com.thealgorithms.others;
+
+/**
+ * Implementation of Knuth–Morris–Pratt algorithm Usage: see the main function
+ * for an example
+ */
+public class KMP {
+    // a working example
+
+    public static void main(String[] args) {
+        final String haystack = "AAAAABAAABA"; // This is the full string
+        final String needle = "AAAA"; // This is the substring that we want to find
+        KMPmatcher(haystack, needle);
+    }
+
+    // find the starting index in string haystack[] that matches the search word P[]
+    public static void KMPmatcher(final String haystack, final String needle) {
+        final int m = haystack.length();
+        final int n = needle.length();
+        final int[] pi = computePrefixFunction(needle);
+        int q = 0;
+        for (int i = 0; i < m; i++) {
+            while (q > 0 && haystack.charAt(i) != needle.charAt(q)) {
+                q = pi[q - 1];
+            }
+
+            if (haystack.charAt(i) == needle.charAt(q)) {
+                q++;
+            }
+
+            if (q == n) {
+                System.out.println("Pattern starts: " + (i + 1 - n));
+                q = pi[q - 1];
+            }
+        }
+    }
+
+    // return the prefix function
+    private static int[] computePrefixFunction(final String P) {
+        final int n = P.length();
+        final int[] pi = new int[n];
+        pi[0] = 0;
+        int q = 0;
+        for (int i = 1; i < n; i++) {
+            while (q > 0 && P.charAt(q) != P.charAt(i)) {
+                q = pi[q - 1];
+            }
+
+            if (P.charAt(q) == P.charAt(i)) {
+                q++;
+            }
+
+            pi[i] = q;
+        }
+        return pi;
+    }
+}