add 1451

Author: fishercoder1534

README.md

@@ -8,6 +8,7 @@ _If you like this project, please leave me a star._ ★
 
 |  #  |      Title     |   Solutions   | Video  | Difficulty  | Tag                   
 |-----|----------------|---------------|--------|-------------|-------------
+|1451|[Rearrange Words in a Sentence](https://leetcode.com/problems/rearrange-words-in-a-sentence/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1451.java) | |Medium|String, Sort|
 |1450|[Number of Students Doing Homework at a Given Time](https://leetcode.com/problems/number-of-students-doing-homework-at-a-given-time/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1450.java) | |Easy|Array|
 |1448|[Count Good Nodes in Binary Tree](https://leetcode.com/problems/count-good-nodes-in-binary-tree/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1448.java) | |Medium|Tree, DFS|
 |1447|[Simplified Fractions](https://leetcode.com/problems/simplified-fractions/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1447.java) | |Medium|Math|

src/main/java/com/fishercoder/solutions/_1451.java

@@ -0,0 +1,34 @@
+package com.fishercoder.solutions;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.TreeMap;
+
+public class _1451 {
+    public static class Solution1 {
+        public String arrangeWords(String text) {
+            TreeMap<Integer, List<String>> map = new TreeMap<>();
+            String[] words = text.split(" ");
+            for (String word : words) {
+                int len = word.length();
+                if (!map.containsKey(len)) {
+                    map.put(len, new ArrayList<>());
+                }
+                map.get(len).add(word.toLowerCase());
+            }
+            StringBuilder sb = new StringBuilder();
+            boolean first = true;
+            for (int len : map.keySet()) {
+                List<String> strings = map.get(len);
+                for (String str : strings) {
+                    if (first) {
+                        str = Character.toUpperCase(str.charAt(0)) + str.substring(1);
+                        first = false;
+                    }
+                    sb.append(str + " ");
+                }
+            }
+            return sb.substring(0, sb.length() - 1);
+        }
+    }
+}

src/test/java/com/fishercoder/_1451Test.java

@@ -0,0 +1,22 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._1451;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static junit.framework.TestCase.assertEquals;
+
+public class _1451Test {
+    private static _1451.Solution1 solution1;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _1451.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals("Is cool leetcode", solution1.arrangeWords("Leetcode is cool"));
+    }
+
+}