add 5087

fishercoder1534 · fishercoder1534 · commit 603fb8b6e9ca · 2019-06-10T05:30:39.000-07:00
diff --git a/README.md b/README.md
@@ -27,6 +27,7 @@ Your ideas/fixes/algorithms are more than welcome!
 
 |  #  |      Title     |   Solutions   | Time          | Space         | Video  | Difficulty  | Tag                   
 |-----|----------------|---------------|---------------|---------------|--------|-------------|-------------
+|5087|[Letter Tile Possibilities](https://leetcode.com/problems/letter-tile-possibilities/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_5087.java) | O(1) | O(1) | |Medium||
 |5083|[Occurrences After Bigram](https://leetcode.com/problems/occurrences-after-bigram/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_5083.java) | O(n) | O(1) | |Easy||
 |1071|[Greatest Common Divisor of Strings](https://leetcode.com/problems/greatest-common-divisor-of-strings/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1071.java) | O(m*n) | O(1) | |Easy||
 |1065|[Index Pairs of a String](https://leetcode.com/problems/index-pairs-of-a-string/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1065.java) | O(nlogn) | O(1) | |Medium||
diff --git a/src/main/java/com/fishercoder/solutions/_5087.java b/src/main/java/com/fishercoder/solutions/_5087.java
@@ -0,0 +1,60 @@
+package com.fishercoder.solutions;
+
+import com.fishercoder.common.utils.CommonUtils;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * 5087. Letter Tile Possibilities
+ *
+ * You have a set of tiles, where each tile has one letter tiles[i] printed on it.
+ * Return the number of possible non-empty sequences of letters you can make.
+ *
+ * Example 1:
+ * Input: "AAB"
+ * Output: 8
+ * Explanation: The possible sequences are "A", "B", "AA", "AB", "BA", "AAB", "ABA", "BAA".
+ *
+ * Example 2:
+ * Input: "AAABBC"
+ * Output: 188
+ *
+ * Note:
+ * 1. 1 <= tiles.length <= 7
+ * 2. tiles consists of uppercase English letters.
+ * */
+public class _5087 {
+    public static class Solution1 {
+        public int numTilePossibilities(String tiles) {
+            char[] chars = tiles.toCharArray();
+            Arrays.sort(chars);
+            boolean[] used = new boolean[chars.length];
+            StringBuilder sb = new StringBuilder();
+            List<String> result = new ArrayList<>();
+            dfs(chars, used, sb, result);
+            CommonUtils.print(result);
+            return result.size();
+        }
+
+        private void dfs(char[] chars, boolean[] used, StringBuilder sb, List<String> result) {
+            if (sb.length() != 0) {
+                result.add(sb.toString());
+            }
+            for (int i = 0; i < chars.length; i++) {
+                if (used[i]) {
+                    continue;
+                }
+                if (i > 0 && chars[i - 1] == chars[i] && !used[i - 1]) {
+                    continue;
+                }
+                used[i] = true;
+                sb.append(chars[i]);
+                dfs(chars, used, sb, result);
+                used[i] = false;
+                sb.deleteCharAt(sb.length() - 1);
+            }
+        }
+    }
+}
diff --git a/src/test/java/com/fishercoder/_5087Test.java b/src/test/java/com/fishercoder/_5087Test.java
@@ -0,0 +1,27 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._5087;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _5087Test {
+    private static _5087.Solution1 solution1;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _5087.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals(8, solution1.numTilePossibilities("AAB"));
+    }
+
+    @Test
+    public void test2() {
+        assertEquals(188, solution1.numTilePossibilities("AAABBC"));
+    }
+
+}
