Algorithms-II : 4-Boggle: implementationalgs-II

1 files changed, 305 insertions, 0 deletions

diff --git a/Algorithms/Part-II/4-Boggle/BoggleSolverDicho.java b/Algorithms/Part-II/4-Boggle/BoggleSolverDicho.java
new file mode 100644
index 0000000..23a645a
--- /dev/null
+++ b/Algorithms/Part-II/4-Boggle/BoggleSolverDicho.java
@@ -0,0 +1,305 @@
+/* vim: set expandtab tabstop=4 shiftwidth=4 : */
+
+import java.util.Set;
+import java.util.HashSet;
+import java.util.Arrays;
+
+public class BoggleSolverDicho
+{
+
+    private class BoggleDictState
+    {
+        private String s;
+        private int idx, from, to;
+        private boolean isWord;
+
+        public BoggleDictState(int from, int to)
+        {
+            this.s = "";
+            this.idx = -1;
+            this.from = from;
+            this.to = to;
+            this.isWord = false;
+        }
+
+        public BoggleDictState(String s, int idx, int from, int to,
+                boolean isWord)
+        {
+            this.s = s;
+            this.idx = idx;
+            this.from = from;
+            this.to = to;
+            this.isWord = isWord;
+        }
+
+        public String s()       { return s; }
+        public int idx()        { return idx; }
+        public int from()       { return from; }
+        public int to()         { return to; }
+        public boolean isWord() { return isWord; }
+        public int n()          { return (to - from + 1); }
+
+        public String toString(String[] words)
+        {
+            String ret = s + "(" + idx + ") " + isWord + " "
+                + " [" + from + ";" + to + "](" + n()+") ";
+
+            if (from > 0) ret += words[from - 1];
+            ret += " ["+words[from]+"..."+words[to]+"] ";
+            if (to < (words.length - 1)) ret += words[to + 1];
+
+            return ret;
+        }
+    }
+
+    private class BoggleDict
+    {
+        private String[] words;
+
+        public BoggleDict(String[] words)
+        {
+            this.words = Arrays.copyOf(words, words.length);
+        }
+
+        public int size()
+        {
+            return words.length;
+        }
+
+        public boolean exists(String word) {
+            if (word.isEmpty()) return false;
+
+            BoggleDictState st = new BoggleDictState(0, (size() - 1));
+            for (int i = 0; i < word.length(); i++) {
+                st = filter(word.charAt(i), st);
+                if (st == null) return false;
+            }
+
+            return  st.isWord();
+        }
+
+        private BoggleDictState filter(char c, BoggleDictState st)
+        {
+            int idx = st.idx() + 1;
+            int from = st.from();
+            int to = st.to();
+            int n = st.n();
+
+            if (words[from].length() <= idx) {
+                if (n == 1) return null;
+                from++;
+            }
+
+            boolean fromOk = (words[from].charAt(idx) == c);
+            boolean toOk = (words[to].charAt(idx) == c);
+
+            if (!fromOk && (n == 1)) return null;
+
+            // if (n < 200) {
+            //     // lower bound
+            //     if (!fromOk) {
+            //         for (int i = from; i <= to; i++) {
+            //             if (words[i].charAt(idx) == c) {
+            //                 fromOk = true;
+            //                 from = i;
+            //                 break;
+            //             }
+            //         }
+            //         if (!fromOk) return null;
+            //     }
+            //     // upper bound
+            //     if (!toOk) {
+            //         for (int i = to; i >= from; i--) {
+            //             if (words[i].charAt(idx) == c) {
+            //                 toOk = true;
+            //                 to = i;
+            //                 break;
+            //             }
+            //         }
+            //         if (!toOk) return null;
+            //     }
+            // }
+            // lower bound
+            if (!fromOk) {
+                int tob = to;
+
+                int mid = (from + tob) / 2;
+                while (mid != from) {
+
+                    int diff = words[mid].charAt(idx) - c;
+
+                    if (diff > 0) {
+                        to = mid;
+                        tob = mid;
+                    } else if (diff < 0)
+                        from = mid;
+                    else
+                        tob = mid;
+
+                    mid = (tob + from) / 2;
+                }
+                if (!(words[from].charAt(idx) == c)) {
+                    if (words[tob].charAt(idx) == c) from = tob;
+                    else return null;
+                }
+            }
+
+            // upper bound
+            if (!toOk) {
+                int fromb = from;
+                int mid = (fromb + to) / 2;
+                while (mid != fromb) {
+
+                    int diff = words[mid].charAt(idx) - c;
+
+                    if (diff <= 0)
+                        fromb = mid;
+                    else
+                        to = mid;
+
+                    mid = (fromb + to) / 2;
+                }
+                if (!(words[to].charAt(idx) == c)) {
+                    if (words[fromb].charAt(idx) == c) to = fromb;
+                    else return null;
+                }
+            }
+
+            boolean isWord = ((idx > 1) && ((words[from].length() - 1) == idx));
+
+            return new BoggleDictState((st.s() + c), idx, from, to, isWord);
+        }
+    }
+
+    private int cols, rows;
+    private BoggleDict dict;
+    private BoggleBoard board;
+    private boolean[] visited;
+    private Set<String> result;
+
+    // assume each word in the dictionary contains only [A-Z]
+    public BoggleSolverDicho(String[] dictionary)
+    {
+        dict = new BoggleDict(dictionary);
+    }
+
+    // Returns the set of all valid words in the given Boggle board
+    public Iterable<String> getAllValidWords(BoggleBoard b)
+    {
+        this.board = b;
+        this.cols = board.cols();
+        this.rows = board.rows();
+        this.result = new HashSet<String>();
+
+        BoggleDictState emptyState = new BoggleDictState(0, (dict.size() - 1));
+        for (int r = 0; r < this.rows; r++) {
+            for (int c = 0; c < this.cols; c++) {
+                this.visited = new boolean[this.rows * this.cols];
+                explore(r, c, emptyState);
+            }
+        }
+
+        return result;
+    }
+
+    //
+    private void explore(int r, int c, BoggleDictState current)
+    {
+        if ((r < 0) || (r >= rows) || (c < 0) || (c >= cols)) return;
+
+        int visitedIdx = (r * this.cols) + c;
+        if (visited[visitedIdx]) return;
+
+        char ch = board.getLetter(r, c);
+        BoggleDictState next = dict.filter(ch, current);
+        if (next == null) return;
+        if (ch == 'Q') {
+            next = dict.filter('U', next);
+            if (next == null) return;
+        }
+
+        if (next.isWord()) result.add(next.s());
+
+        visited[visitedIdx] = true;
+
+        explore((r - 1), (c - 1), next);
+        explore((r - 1), c, next);
+        explore((r - 1), (c + 1), next);
+        explore(r, (c - 1), next);
+        explore(r, (c + 1), next);
+        explore((r + 1), (c - 1), next);
+        explore((r + 1), c, next);
+        explore((r + 1), (c + 1), next);
+
+        visited[visitedIdx] = false;
+    }
+
+    // Returns the score if it is in the dictionary, zero otherwise.
+    // assume the word contains only [A-Z]
+    public int scoreOf(String word)
+    {
+        if (!dict.exists(word)) return 0;
+
+        int l = word.length();
+        if (l < 3) {
+            return 0;
+        } else if (l < 5) {
+            return 1;
+        } else if (l < 6) {
+            return 2;
+        } else if (l < 7) {
+            return 3;
+        } else if (l < 8) {
+            return 5;
+        } else {
+            return 11;
+        }
+    }
+
+    public static void main(String[] args)
+    {
+        if (args[0].equals("timing")) {
+            In in = new In("./data/dictionary-yawl.txt");
+            String[] dictionary = in.readAllStrings();
+
+            Stopwatch w = new Stopwatch();
+            BoggleSolver solver = new BoggleSolver(dictionary);
+            double dt = +w.elapsedTime();
+            System.out.println("construction : "+dt);
+
+            String s = "board-pneumonoultramicroscopicsilicovolcanoconiosis.txt";
+            BoggleBoard []boards = new BoggleBoard[5];
+            boards[0] = new BoggleBoard("./data/board-points4527.txt");
+            boards[1] = new BoggleBoard("./data/board-points13464.txt");
+            boards[2] = new BoggleBoard("./data/board-points4410.txt");
+            boards[3] = new BoggleBoard("./data/board-points1250.txt");
+            boards[4] = new BoggleBoard("./data/board-points1500.txt");
+            // boards[1] = new BoggleBoard("./data/board-rotavator.txt");
+            // boards[2] = new BoggleBoard("./data/board-16q.txt");
+            // boards[4] = new BoggleBoard("./data/" + s);
+
+
+            for (int t = 0; t < 5; t++) {
+                w = new Stopwatch();
+                for (int i = 0; i < 3000; i++) {
+                    solver.getAllValidWords(boards[i % 5]);
+                }
+                dt = +w.elapsedTime();
+                System.out.println("search time : "+dt);
+            }
+        } else {
+            In in = new In(args[0]);
+            String[] dictionary = in.readAllStrings();
+            BoggleSolverDicho solver = new BoggleSolverDicho(dictionary);
+            BoggleBoard board = new BoggleBoard(args[1]);
+            int score = 0;
+            for (String word : solver.getAllValidWords(board))
+            {
+                StdOut.println(word);
+                score += solver.scoreOf(word);
+            }
+            StdOut.println("Score = " + score);
+            StdOut.println("Score = " + solver.scoreOf("REQUEST"));
+        }
+    }
+}