add : NaivePatternSearch.java

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

@@ -0,0 +1,44 @@
+package com.thealgorithms.strings;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public final class NaivePatternSearch {
+
+    // Private constructor to prevent instantiation
+    private NaivePatternSearch() {
+        throw new UnsupportedOperationException("Utility class");
+    }
+
+    /**
+     * Naive pattern searching algorithm.
+     *
+     * @param text the text to be searched
+     * @param pattern the pattern to search for
+     * @return list of starting indices where pattern is found
+     * @throws IllegalArgumentException if text or pattern is null
+     */
+    public static List<Integer> search(String text, String pattern) {
+        if (text == null || pattern == null) {
+            throw new IllegalArgumentException("Text and pattern must not be null");
+        }
+
+        List<Integer> result = new ArrayList<>();
+        int n = text.length();
+        int m = pattern.length();
+
+        for (int i = 0; i <= n - m; i++) {
+            int j;
+            for (j = 0; j < m; j++) {
+                if (text.charAt(i + j) != pattern.charAt(j)) {
+                    break;
+                }
+            }
+            if (j == m) {
+                result.add(i);
+            }
+        }
+
+        return result;
+    }
+}