Day ??? - Graph Search Algorithm III

GraphSearchAlgorithmIII.java

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+import java.util.*;
+
+public class GraphSearchAlgorithmIII {
+    /**
+     * Largest Product Of Length
+     * <p>
+     * Given a dictionary containing many words, find the largest product of two
+     * words’ lengths, such that the two words do not share any common characters.
+     */
+    public int largestProduct(String[] dict) {
+        Arrays.sort(dict, new Comparator<String>() {
+            @Override
+            public int compare(String a, String b) {
+                return b.length() - a.length();
+            }
+        });
+
+        int[] bitmap = buildBitmap(dict);
+        int n = dict.length;
+
+        PriorityQueue<Pair> pq = new PriorityQueue<>();
+
+        pq.offer(new Pair(0, 0, dict, bitmap));
+        boolean[][] visited = new boolean[n][n];
+        visited[0][0] = true;
+
+        while (!pq.isEmpty()) {
+            Pair cur = pq.poll();
+            if (!cur.hasCommon()) {
+                return cur.prod();
+            }
+            int i = cur.i;
+            int j = cur.j;
+            if (i < n - 1 && !visited[i + 1][j]) {
+                visited[i + 1][j] = true;
+                pq.offer(new Pair(i + 1, j, dict, bitmap));
+            }
+            if (j < n - 1 && !visited[i][j + 1]) {
+                visited[i][j + 1] = true;
+                pq.offer(new Pair(i, j + 1, dict, bitmap));
+            }
+
+        }
+
+        return 0;
+    }
+
+    private class Pair implements Comparable<Pair> {
+        public int i;
+        public int j;
+        private String[] dict;
+        private int[] bitmap;
+
+        public Pair(int i, int j, String[] dict, int[] bitmap) {
+            this.i = i;
+            this.j = j;
+            this.dict = dict;
+            this.bitmap = bitmap;
+        }
+
+        @Override
+        public int compareTo(Pair other) {
+            return other.prod() - this.prod();
+        }
+
+        public int prod() {
+            return dict[i].length() * dict[j].length();
+        }
+
+        public boolean hasCommon() {
+            return (bitmap[i] & bitmap[j]) != 0;
+        }
+    }
+
+    private int[] buildBitmap(String[] dict) {
+        int[] bitmap = new int[dict.length];
+        for (int i = 0; i < dict.length; i++) {
+            String cur = dict[i];
+            int bits = 0;
+            for (int j = 0; j < cur.length(); j++) {
+                bits |= (1 << (cur.charAt(j) - 'a'));
+            }
+            bitmap[i] = bits;
+        }
+        return bitmap;
+    }
+
+    /**
+     * Kth Smallest With Only 3, 5, 7 As Factors
+     * <p>
+     * Find the Kth smallest number s such that s = 3 ^ x * 5 ^ y * 7 ^ z, x > 0 and
+     * y > 0 and z > 0, x, y, z are all integers.
+     */
+    public long kth(int k) {
+        if (k == 1) {
+            return 105L;
+        }
+        PriorityQueue<Long> pq = new PriorityQueue<>();
+        Set<Long> set = new HashSet<>();
+
+        pq.offer(105L);
+        while (--k > 0) {
+            long cur = pq.poll();
+            if (!set.contains(cur * 3)) {
+                pq.offer(cur * 3);
+                set.add(cur * 3);
+            }
+            if (!set.contains(cur * 5)) {
+                pq.offer(cur * 5);
+                set.add(cur * 5);
+            }
+            if (!set.contains(cur * 7)) {
+                pq.offer(cur * 7);
+                set.add(cur * 7);
+            }
+        }
+
+        return pq.peek();
+    }
+
+    /**
+     * Kth Closest Point To <0,0,0>
+     * <p>
+     * Given three arrays sorted in ascending order. Pull one number from each array
+     * to form a coordinate <x,y,z> in a 3D space. Find the coordinates of the
+     * points that is k-th closest to <0,0,0>.
+     */
+    public List<Integer> closest(int[] a, int[] b, int[] c, int k) {
+        int al = a.length;
+        int bl = b.length;
+        int cl = c.length;
+        boolean[][][] visited = new boolean[al][bl][cl];
+        PriorityQueue<Coord> pq = new PriorityQueue<>();
+
+        return null;
+    }
+
+    private class Coord implements Comparable<Coord> {
+        @Override
+        public int compareTo(Coord other) {
+            return 0;
+        }
+    }
+}