Naive algorithm for Pattern Searching Last Updated : 20 Apr, 2024 Comments Improve Suggest changes Like Article Like Report Given text string with length n and a pattern with length m, the task is to prints all occurrences of pattern in text. Note: You may assume that n > m. Examples: Input: text = "THIS IS A TEST TEXT", pattern = "TEST"Output: Pattern found at index 10 Input: text = "AABAACAADAABAABA", pattern = "AABA"Output: Pattern found at index 0, Pattern found at index 9, Pattern found at index 12 Pattern searchingRecommended: Please solve it on “PRACTICE ” first, before moving on to the solution. Naive Pattern Searching algorithm: Slide the pattern over text one by one and check for a match. If a match is found, then slide by 1 again to check for subsequent matches. C++ #include <iostream> #include <string> using namespace std; void search(string& pat, string& txt) { int M = pat.size(); int N = txt.size(); // A loop to slide pat[] one by one for (int i = 0; i <= N - M; i++) { int j; // For current index i, check for pattern match for (j = 0; j < M; j++) { if (txt[i + j] != pat[j]) { break; } } // If pattern matches at index i if (j == M) { cout << "Pattern found at index " << i << endl; } } } // Driver's Code int main() { // Example 1 string txt1 = "AABAACAADAABAABA"; string pat1 = "AABA"; cout << "Example 1: " << endl; search(pat1, txt1); // Example 2 string txt2 = "agd"; string pat2 = "g"; cout << "\nExample 2: " << endl; search(pat2, txt2); return 0; } C #include <stdio.h> #include <string.h> void search(char* pat, char* txt) { int M = strlen(pat); int N = strlen(txt); // A loop to slide pat[] one by one for (int i = 0; i <= N - M; i++) { int j; // For current index i, check for pattern match for (j = 0; j < M; j++) { if (txt[i + j] != pat[j]) { break; } } // If pattern matches at index i if (j == M) { printf("Pattern found at index %d\n", i); } } } int main() { // Example 1 char txt1[] = "AABAACAADAABAABA"; char pat1[] = "AABA"; printf("Example 1:\n"); search(pat1, txt1); // Example 2 char txt2[] = "agd"; char pat2[] = "g"; printf("\nExample 2:\n"); search(pat2, txt2); return 0; } Java public class PatternSearch { public static void search(String pat, String txt) { int M = pat.length(); int N = txt.length(); // A loop to slide pat[] one by one for (int i = 0; i <= N - M; i++) { int j; // For current index i, check for pattern match for (j = 0; j < M; j++) { if (txt.charAt(i + j) != pat.charAt(j)) { break; } } // If pattern matches at index i if (j == M) { System.out.println("Pattern found at index " + i); } } } public static void main(String[] args) { // Example 1 String txt1 = "AABAACAADAABAABA"; String pat1 = "AABA"; System.out.println("Example 1:"); search(pat1, txt1); // Example 2 String txt2 = "agd"; String pat2 = "g"; System.out.println("\nExample 2:"); search(pat2, txt2); } } Python3 def search_pattern(pattern, text): # Get the lengths of the pattern and the text m = len(pattern) n = len(text) # A loop to slide pattern over text one by one for i in range(n - m + 1): # For current index i, check for pattern match j = 0 while j < m and text[i + j] == pattern[j]: j += 1 # If the entire pattern matches the text starting at index i if j == m: print(f"Pattern found at index {i}") # Example usage if __name__ == "__main__": # Example 1 text1 = "AABAACAADAABAABA" pattern1 = "AABA" print("Example 1:") search_pattern(pattern1, text1) # Example 2 text2 = "agd" pattern2 = "g" print("\nExample 2:") search_pattern(pattern2, text2) C# using System; class PatternSearch { static void Search(string pat, string txt) { int M = pat.Length; int N = txt.Length; // A loop to slide pat[] one by one for (int i = 0; i <= N - M; i++) { int j; // For current index i, check for pattern match for (j = 0; j < M; j++) { if (txt[i + j] != pat[j]) { break; } } // If pattern matches at index i if (j == M) { Console.WriteLine($"Pattern found at index {i}"); } } } static void Main() { // Example 1 string txt1 = "AABAACAADAABAABA"; string pat1 = "AABA"; Console.WriteLine("Example 1:"); Search(pat1, txt1); // Example 2 string txt2 = "agd"; string pat2 = "g"; Console.WriteLine("\nExample 2:"); Search(pat2, txt2); } } JavaScript function search(pat, txt) { const M = pat.length; const N = txt.length; // A loop to slide pat[] one by one for (let i = 0; i <= N - M; i++) { let j = 0; // For current index i, check for pattern match while (j < M && txt[i + j] === pat[j]) { j++; } // If pattern matches at index i if (j === M) { console.log(`Pattern found at index ${i}`); } } } // Example 1 const txt1 = "AABAACAADAABAABA"; const pat1 = "AABA"; console.log("Example 1:"); search(pat1, txt1); // Example 2 const txt2 = "agd"; const pat2 = "g"; console.log("\nExample 2:"); search(pat2, txt2); PHP function search($pat, $txt) { $M = strlen($pat); $N = strlen($txt); // A loop to slide pat[] one by one for ($i = 0; $i <= $N - $M; $i++) { $j = 0; // For current index i, check for pattern match while ($j < $M && $txt[$i + $j] === $pat[$j]) { $j++; } // If pattern matches at index i if ($j == $M) { echo "Pattern found at index $i\n"; } } } // Example 1 $txt1 = "AABAACAADAABAABA"; $pat1 = "AABA"; echo "Example 1:\n"; search($pat1, $txt1); // Example 2 $txt2 = "agd"; $pat2 = "g"; echo "\nExample 2:\n"; search($pat2, $txt2); OutputPattern found at index 0 Pattern found at index 9 Pattern found at index 13 Time Complexity: O(N2)Auxiliary Space: O(1) Complexity Analysis of Naive algorithm for Pattern Searching:Best Case: O(n)When the pattern is found at the very beginning of the text (or very early on).The algorithm will perform a constant number of comparisons, typically on the order of O(n) comparisons, where n is the length of the pattern.Worst Case: O(n2)When the pattern doesn't appear in the text at all or appears only at the very end.The algorithm will perform O((n-m+1)*m) comparisons, where n is the length of the text and m is the length of the pattern.In the worst case, for each position in the text, the algorithm may need to compare the entire pattern against the text. Comment More infoAdvertise with us Next Article Rabin-Karp Algorithm for Pattern Searching K kartik Follow Improve Article Tags : Strings Pattern Searching DSA Oracle Qualcomm Payu MAQ Software +3 More Practice Tags : MAQ SoftwareOraclePayuQualcommPattern SearchingStrings +2 More Similar Reads What is Pattern Searching ? Pattern searching in Data Structures and Algorithms (DSA) is a fundamental concept that involves searching for a specific pattern or sequence of elements within a given data structure. This technique is commonly used in string matching algorithms to find occurrences of a particular pattern within a 5 min read Introduction to Pattern Searching - Data Structure and Algorithm Tutorial Pattern searching is an algorithm that involves searching for patterns such as strings, words, images, etc. We use certain algorithms to do the search process. The complexity of pattern searching varies from algorithm to algorithm. They are very useful when performing a search in a database. The Pat 15+ min read Naive algorithm for Pattern Searching Given text string with length n and a pattern with length m, the task is to prints all occurrences of pattern in text. Note: You may assume that n > m. Examples: Input:  text = "THIS IS A TEST TEXT", pattern = "TEST"Output: Pattern found at index 10 Input:  text =  "AABAACAADAABAABA", pattern = 6 min read Rabin-Karp Algorithm for Pattern Searching Given two strings text and pattern string, your task is to find all starting positions where the pattern appears as a substring within the text. The strings will only contain lowercase English alphabets.While reporting the results, use 1-based indexing (i.e., the first character of the text is at po 12 min read KMP Algorithm for Pattern Searching Given two strings txt and pat, the task is to return all indices of occurrences of pat within txt. Examples:Input: txt = "abcab", pat = "ab"Output: [0, 3]Explanation: The string "ab" occurs twice in txt, first occurrence starts from index 0 and second from index 3.Input: txt= "aabaacaadaabaaba", pat 14 min read Z algorithm (Linear time pattern searching Algorithm) This algorithm efficiently locates all instances of a specific pattern within a text in linear time. If the length of the text is "n" and the length of the pattern is "m," then the total time taken is O(m + n), with a linear auxiliary space. It is worth noting that the time and auxiliary space of th 13 min read Finite Automata algorithm for Pattern Searching Given a text txt[0..n-1] and a pattern pat[0..m-1], write a function search(char pat[], char txt[]) that prints all occurrences of pat[] in txt[]. 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Exampl 15+ min read ÂÂkasai’s Algorithm for Construction of LCP array from Suffix Array Background Suffix Array : A suffix array is a sorted array of all suffixes of a given string. Let the given string be "banana". 0 banana 5 a1 anana Sort the Suffixes 3 ana2 nana ----------------> 1 anana 3 ana alphabetically 0 banana 4 na 4 na 5 a 2 nanaThe suffix array for "banana" :suffix[] = { 15+ min read Like