Update BoyerMoore.java

PauLopNun · web-flow · commit 3734afad146c · 2025-06-08T18:18:29.000+02:00
diff --git a/src/main/java/com/thealgorithms/searches/BoyerMoore.java b/src/main/java/com/thealgorithms/searches/BoyerMoore.java
@@ -1,9 +1,7 @@
-package com.thealgorithms.searches;
-
 /**
  * Boyer-Moore string search algorithm
  * Efficient algorithm for substring search.
- * https://en.wikipedia.org/wiki/Boyer%E2%80%93Moore_string-search-algorithm
+ * https://en.wikipedia.org/wiki/Boyer%E2%80%93Moore_string-search_algorithm
  */
 public class BoyerMoore {
 
@@ -13,34 +11,40 @@ public class BoyerMoore {
 
     public BoyerMoore(String pat) {
         this.pattern = pat;
-        this.R = 256;
+        this.R = 256; // extended ASCII
         this.right = new int[R];
+
+        // Initialize all occurrences as -1
         for (int c = 0; c < R; c++) {
             right[c] = -1;
         }
+
+        // Fill the actual value of last occurrence of a character
         for (int j = 0; j < pat.length(); j++) {
             right[pat.charAt(j)] = j;
         }
     }
 
     public int search(String text) {
+        if (pattern.isEmpty()) return 0;
+
         int m = pattern.length();
         int n = text.length();
-        int skip;
 
+        int skip;
         for (int i = 0; i <= n - m; i += skip) {
             skip = 0;
             for (int j = m - 1; j >= 0; j--) {
-                if (pattern.charAt(j) != text.charAt(i + j)) {
-                    skip = Math.max(1, j - right[text.charAt(i + j)]);
+                char txtChar = text.charAt(i + j);
+                char patChar = pattern.charAt(j);
+                if (patChar != txtChar) {
+                    skip = Math.max(1, j - right[txtChar]);
                     break;
                 }
             }
-            if (skip == 0) {
-                return i;
-            }
+            if (skip == 0) return i; // found
         }
-        return -1;
+        return -1; // not found
     }
 
     public static int search(String text, String pattern) {
