add 1456

Author: fishercoder1534

README.md

@@ -8,6 +8,7 @@ _If you like this project, please leave me a star._ ★
 
 |  #  |      Title     |   Solutions   | Video  | Difficulty  | Tag                   
 |-----|----------------|---------------|--------|-------------|-------------
+|1456|[ Maximum Number of Vowels in a Substring of Given Length](https://leetcode.com/problems/maximum-number-of-vowels-in-a-substring-of-given-length/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1456.java) | |Easy|String, Sliding Window|
 |1455|[Check If a Word Occurs As a Prefix of Any Word in a Sentence](https://leetcode.com/problems/check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1455.java) | |Easy|String|
 |1452|[People Whose List of Favorite Companies Is Not a Subset of Another List](https://leetcode.com/problems/people-whose-list-of-favorite-companies-is-not-a-subset-of-another-list/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1452.java) | |Medium|String, Sort|
 |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|

src/main/java/com/fishercoder/solutions/_1456.java

@@ -0,0 +1,48 @@
+package com.fishercoder.solutions;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+public class _1456 {
+    public static class Solution1 {
+        public int maxVowels(String s, int k) {
+            Map<Character, Integer> vowels = new HashMap<>();
+            Set<Character> set = new HashSet<>();
+            set.add('a');
+            set.add('e');
+            set.add('i');
+            set.add('o');
+            set.add('u');
+            int left = 0;
+            for (; left < k; left++) {
+                if (set.contains(s.charAt(left))) {
+                    vowels.put(s.charAt(left), vowels.getOrDefault(s.charAt(left), 0) + 1);
+                }
+            }
+            int max = 0;
+            for (char c : vowels.keySet()) {
+                max += vowels.get(c);
+            }
+            int right = left;
+            left = 0;
+            for (; right < s.length(); right++, left++) {
+                char leftChar = s.charAt(left);
+                if (set.contains(leftChar) && vowels.containsKey(leftChar) && vowels.get(leftChar) > 0) {
+                    vowels.put(leftChar, vowels.get(leftChar) - 1);
+                }
+                char rightChar = s.charAt(right);
+                if (set.contains(rightChar)) {
+                    vowels.put(rightChar, vowels.getOrDefault(rightChar, 0) + 1);
+                }
+                int thisMax = 0;
+                for (char c : vowels.keySet()) {
+                    thisMax += vowels.get(c);
+                }
+                max = Math.max(max, thisMax);
+            }
+            return max;
+        }
+    }
+}

src/test/java/com/fishercoder/_1456Test.java

@@ -0,0 +1,22 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._1456;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static junit.framework.TestCase.assertEquals;
+
+public class _1456Test {
+    private static _1456.Solution1 solution1;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _1456.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals(3, solution1.maxVowels("abciiidef", 3));
+    }
+
+}