diff --git a/src/main/java/com/ctci/treesandgraphs/pattern_search.java b/src/main/java/com/ctci/treesandgraphs/pattern_search.java new file mode 100644 index 00000000..bf8401e3 --- /dev/null +++ b/src/main/java/com/ctci/treesandgraphs/pattern_search.java @@ -0,0 +1,109 @@ +import java.util.LinkedList; +import java.util.List; +class SuffixTrieNode { + + final static int MAX_CHAR = 256; + + SuffixTrieNode[] children = new SuffixTrieNode[MAX_CHAR]; + List indexes; + + SuffixTrieNode() + { + + indexes = new LinkedList(); + + for (int i = 0; i < MAX_CHAR; i++) + children[i] = null; + } + + + void insertSuffix(String s, int index) { + + + indexes.add(index); + + + if (s.length() > 0) { + + + char cIndex = s.charAt(0); + + + + if (children[cIndex] == null) + children[cIndex] = new SuffixTrieNode(); + + // Recur for next suffix + children[cIndex].insertSuffix(s.substring(1), + index + 1); + } + } + + + List search(String s) { + + + if (s.length() == 0) + return indexes; + + + if (children[s.charAt(0)] != null) + return (children[s.charAt(0)]).search(s.substring(1)); + + + else + return null; + } +} + +// A Trie of all suffixes +class Suffix_tree{ + + SuffixTrieNode root = new SuffixTrieNode(); + + + Suffix_tree(String txt) { + + + for (int i = 0; i < txt.length(); i++) + root.insertSuffix(txt.substring(i), i); + } + + void search_tree(String pat) { + + + List result = root.search(pat); + + + if (result == null) + System.out.println("Pattern not found"); + else { + + int patLen = pat.length(); + + for (Integer i : result) + System.out.println("Pattern found at position " + + (i - patLen)); + } + } + + + public static void main(String args[]) { + + + String txt = "geeksforgeeks.org"; + Suffix_tree S = new Suffix_tree(txt); + + System.out.println("Search for 'ee'"); + S.search_tree("ee"); + + System.out.println("\nSearch for 'geek'"); + S.search_tree("geek"); + + System.out.println("\nSearch for 'quiz'"); + S.search_tree("quiz"); + + System.out.println("\nSearch for 'forgeeks'"); + S.search_tree("forgeeks"); + } +} \ No newline at end of file pFad - Phonifier reborn

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