add 1370

fishercoder1534 · fishercoder1534 · commit bb86214c9bf2 · 2020-03-07T14:03:24.000-08:00
diff --git a/README.md b/README.md
@@ -9,6 +9,7 @@ _If you like this project, please leave me a star._ &#9733;
 |  #  |      Title     |   Solutions   | Video  | Difficulty  | Tag                   
 |-----|----------------|---------------|--------|-------------|-------------
 |1371|[Find the Longest Substring Containing Vowels in Even Counts](https://leetcode.com/problems/find-the-longest-substring-containing-vowels-in-even-counts/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1371.java) | |Medium||String
+|1370|[Increasing Decreasing String](https://leetcode.com/problems/increasing-decreasing-string/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1370.java) | |Easy||String, Sort
 |1367|[Linked List in Binary Tree](https://leetcode.com/problems/linked-list-in-binary-tree/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1367.java) | |Medium||DP, Linked List, Tree
 |1366|[Rank Teams by Votes](https://leetcode.com/problems/rank-teams-by-votes/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1366.java) | |Medium||Array, Sort
 |1365|[How Many Numbers Are Smaller Than the Current Number](https://leetcode.com/problems/how-many-numbers-are-smaller-than-the-current-number/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1365.java) | |Easy||Array, HashTable
diff --git a/src/main/java/com/fishercoder/solutions/_1370.java b/src/main/java/com/fishercoder/solutions/_1370.java
@@ -0,0 +1,74 @@
+package com.fishercoder.solutions;
+
+/**
+ * 1370. Increasing Decreasing String
+ *
+ * Given a string s. You should re-order the string using the following algorithm:
+ * Pick the smallest character from s and append it to the result.
+ * Pick the smallest character from s which is greater than the last appended character to the result and append it.
+ * Repeat step 2 until you cannot pick more characters.
+ * Pick the largest character from s and append it to the result.
+ * Pick the largest character from s which is smaller than the last appended character to the result and append it.
+ * Repeat step 5 until you cannot pick more characters.
+ * Repeat the steps from 1 to 6 until you pick all characters from s.
+ * In each step, If the smallest or the largest character appears more than once you can choose any occurrence and append it to the result.
+ * Return the result string after sorting s with this algorithm.
+ *
+ * Example 1:
+ * Input: s = "aaaabbbbcccc"
+ * Output: "abccbaabccba"
+ * Explanation: After steps 1, 2 and 3 of the first iteration, result = "abc"
+ * After steps 4, 5 and 6 of the first iteration, result = "abccba"
+ * First iteration is done. Now s = "aabbcc" and we go back to step 1
+ * After steps 1, 2 and 3 of the second iteration, result = "abccbaabc"
+ * After steps 4, 5 and 6 of the second iteration, result = "abccbaabccba"
+ *
+ * Example 2:
+ * Input: s = "rat"
+ * Output: "art"
+ * Explanation: The word "rat" becomes "art" after re-ordering it with the mentioned algorithm.
+ *
+ * Example 3:
+ * Input: s = "leetcode"
+ * Output: "cdelotee"
+ *
+ * Example 4:
+ * Input: s = "ggggggg"
+ * Output: "ggggggg"
+ *
+ * Example 5:
+ * Input: s = "spo"
+ * Output: "ops"
+ *
+ * Constraints:
+ * 1 <= s.length <= 500
+ * s contains only lower-case English letters.
+ * */
+public class _1370 {
+    public static class Solution1 {
+        public String sortString(String s) {
+            int[] count = new int[26];
+            for (char c : s.toCharArray()) {
+                count[c - 'a']++;
+            }
+            StringBuilder sb = new StringBuilder();
+            while (sb.length() < s.length()) {
+                for (int i = 0; i < count.length; i++) {
+                    if (count[i] != 0) {
+                        char character = (char) (i + 'a');
+                        sb.append(character);
+                        count[i]--;
+                    }
+                }
+                for (int i = 25; i>= 0; i--) {
+                    if (count[i] > 0) {
+                        char character = (char) (i + 'a');
+                        sb.append(character);
+                        count[i]--;
+                    }
+                }
+            }
+            return sb.toString();
+        }
+    }
+}
diff --git a/src/test/java/com/fishercoder/_1370Test.java b/src/test/java/com/fishercoder/_1370Test.java
@@ -0,0 +1,42 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._1370;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _1370Test {
+    private static _1370.Solution1 solution1;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _1370.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals("abccbaabccba", solution1.sortString("aaaabbbbcccc"));
+    }
+
+    @Test
+    public void test2() {
+        assertEquals("art", solution1.sortString("rat"));
+    }
+
+    @Test
+    public void test3() {
+        assertEquals("cdelotee", solution1.sortString("leetcode"));
+    }
+
+    @Test
+    public void test4() {
+        assertEquals("ggggggg", solution1.sortString("ggggggg"));
+    }
+
+    @Test
+    public void test5() {
+        assertEquals("ops", solution1.sortString("spo"));
+    }
+
+}
