Format KnuthMorrisPratt.java with proper indentation and Javadoc

Author: sriieeu

src/main/java/com/thealgorithms/strings/KnuthMorrisPratt.java

@@ -3,72 +3,94 @@
 import java.util.ArrayList;
 import java.util.List;
 
-
+/**
+ * Implementation of the Knuth–Morris–Pratt (KMP) string matching algorithm.
+ * KMP efficiently searches for occurrences of a pattern within a text by
+ * utilizing a pre-computed failure function to avoid redundant comparisons.
+ * Time Complexity: O(n + m) where n is text length and m is pattern length.
+ */
 final class KnuthMorrisPratt {
-	private KnuthMorrisPratt() {
-	}
+  private KnuthMorrisPratt() {}
 
-	// Compute the longest proper prefix which is also suffix (LPS) array
-	public static int[] computeLps(final String pattern) {
-		final int n = pattern.length();
-		final int[] lps = new int[n];
-		int len = 0; // length of the previous longest prefix suffix
-		lps[0] = 0;
-		for (int i = 1; i < n; ) {
-			if (pattern.charAt(i) == pattern.charAt(len)) {
-				len++;
-				lps[i] = len;
-				i++;
-			} else {
-				if (len != 0) {
-					len = lps[len - 1];
-				} else {
-					lps[i] = 0;
-					i++;
-				}
-			}
-		}
-		return lps;
-	}
+  /**
+   * Compute the Longest Proper Prefix which is also Suffix (LPS) array
+   * for the given pattern. This array is used to avoid unnecessary
+   * character comparisons during the search phase.
+   *
+   * @param pattern the pattern to compute LPS for
+   * @return the LPS array
+   */
+  public static int[] computeLps(final String pattern) {
+    final int n = pattern.length();
+    final int[] lps = new int[n];
+    int len = 0;
+    lps[0] = 0;
+    for (int i = 1; i < n; ) {
+      if (pattern.charAt(i) == pattern.charAt(len)) {
+        len++;
+        lps[i] = len;
+        i++;
+      } else {
+        if (len != 0) {
+          len = lps[len - 1];
+        } else {
+          lps[i] = 0;
+          i++;
+        }
+      }
+    }
+    return lps;
+  }
 
-	// Return list of start indices where pattern occurs in text
-	public static List<Integer> search(final String text, final String pattern) {
-		final List<Integer> occurrences = new ArrayList<>();
-		if (pattern == null || pattern.isEmpty() || text == null) {
-			return occurrences;
-		}
+  /**
+   * Search for all occurrences of the pattern in the text.
+   * Returns a list of starting indices where the pattern is found.
+   *
+   * @param text the text to search in
+   * @param pattern the pattern to search for
+   * @return list of starting indices of pattern occurrences
+   */
+  public static List<Integer> search(final String text, final String pattern) {
+    final List<Integer> occurrences = new ArrayList<>();
+    if (pattern == null || pattern.isEmpty() || text == null) {
+      return occurrences;
+    }
 
-		final int[] lps = computeLps(pattern);
-		int i = 0; // index for text
-		int j = 0; // index for pattern
-		final int n = text.length();
-		final int m = pattern.length();
-		while (i < n) {
-			if (text.charAt(i) == pattern.charAt(j)) {
-				i++;
-				j++;
-				if (j == m) {
-					occurrences.add(i - j);
-					j = lps[j - 1];
-				}
-			} else {
-				if (j != 0) {
-					j = lps[j - 1];
-				} else {
-					i++;
-				}
-			}
-		}
-		return occurrences;
-	}
+    final int[] lps = computeLps(pattern);
+    int i = 0;
+    int j = 0;
+    final int n = text.length();
+    final int m = pattern.length();
+    while (i < n) {
+      if (text.charAt(i) == pattern.charAt(j)) {
+        i++;
+        j++;
+        if (j == m) {
+          occurrences.add(i - j);
+          j = lps[j - 1];
+        }
+      } else {
+        if (j != 0) {
+          j = lps[j - 1];
+        } else {
+          i++;
+        }
+      }
+    }
+    return occurrences;
+  }
 
-	// example runner
-	public static void main(String[] args) {
-		final String text = "AAAAABAAABA";
-		final String pattern = "AAAA";
-		final List<Integer> idx = search(text, pattern);
-		for (int pos : idx) {
-			System.out.println("Pattern starts: " + pos);
-		}
-	}
+  /**
+   * Main method demonstrating the KMP algorithm with an example.
+   *
+   * @param args command line arguments (unused)
+   */
+  public static void main(String[] args) {
+    final String text = "AAAAABAAABA";
+    final String pattern = "AAAA";
+    final List<Integer> idx = search(text, pattern);
+    for (int pos : idx) {
+      System.out.println("Pattern found at index: " + pos);
+    }
+  }
 }