/****************************************************************************** * Compilation: javac KWIK.java * Execution: java KWIK file.txt * Dependencies: StdIn.java StdOut.java In.java SuffixArray.java * Data files: https://algs4.cs.princeton.edu/63suffix/tale.txt * https://algs4.cs.princeton.edu/63suffix/mobydick.txt * * Keyword-in-context search. * * % java KWIK tale.txt 15 * majesty * most gracious majesty king george th * rnkeys and the majesty of the law fir * on against the majesty of the people * se them to his majestys chief secreta * h lists of his majestys forces and of * * the worst * w the best and the worst are known to y * f them give me the worst first there th * for in case of the worst is a friend in * e roomdoor and the worst is over then a * pect mr darnay the worst its the wisest * is his brother the worst of a bad race * ss in them for the worst of health for * you have seen the worst of her agitati * cumwented into the worst of luck buuust * n your brother the worst of the bad rac * full share in the worst of the day pla * mes to himself the worst of the strife * f times it was the worst of times it wa * ould hope that the worst was over well * urage business the worst will be over i * clesiastics of the worst world worldly * ******************************************************************************/ /** * The {@code KWIK} class provides a {@link SuffixArray} client for computing * all occurrences of a keyword in a given string, with surrounding context. * This is known as keyword-in-context search. *

* For additional documentation, * see Section 6.3 of * Algorithms, 4th Edition by Robert Sedgewick and Kevin Wayne. * * @author Robert Sedgewick * @author Kevin Wayne */ public class KWIK { // Do not instantiate. private KWIK() { } /** * Reads a string from a file specified as the first * command-line argument; read an integer k specified as the * second command line argument; then repeatedly processes * use queries, printing all occurrences of the given query * string in the text string with k characters of surrounding * context on either side. * * @param args the command-line arguments */ public static void main(String[] args) { In in = new In(args[0]); int context = Integer.parseInt(args[1]); // read in text String text = in.readAll().replaceAll("\\s+", " "); int n = text.length(); // build suffix array SuffixArray sa = new SuffixArray(text); // find all occurrences of queries and give context while (StdIn.hasNextLine()) { String query = StdIn.readLine(); for (int i = sa.rank(query); i < n; i++) { int from1 = sa.index(i); int to1 = Math.min(n, from1 + query.length()); if (!query.equals(text.substring(from1, to1))) break; int from2 = Math.max(0, sa.index(i) - context); int to2 = Math.min(n, sa.index(i) + context + query.length()); StdOut.println(text.substring(from2, to2)); } StdOut.println(); } } }