add 771

Author: fishercoder1534

Diff for: README.md

@@ -22,6 +22,7 @@ Your ideas/fixes/algorithms are more than welcome!
 
 |  #  |      Title     |   Solutions   | Time          | Space         | Video  | Difficulty  | Tag                   
 |-----|----------------|---------------|---------------|---------------|--------|-------------|-------------
+|771|[Jewels and Stones](https://leetcode.com/problems/jewels-and-stones/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_771.java) | O(n) | O(m) | |Easy|
 |767|[Reorganize String](https://leetcode.com/problems/reorganize-string/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_767.java) | O(klogk) k is the number of unique characters in given String| O(k) | |Medium|
 |766|[Toeplitz Matrix](https://leetcode.com/problems/toeplitz-matrix/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_766.java) | O(m*n) | O(1) | |Easy|
 |765|[Couples Holding Hands](https://leetcode.com/problems/couples-holding-hands/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_765.java) | O(n^2) | O(1) | |Hard| 

Diff for: src/main/java/com/fishercoder/solutions/_771.java

@@ -0,0 +1,43 @@
+package com.fishercoder.solutions;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * 771. Jewels and Stones
+
+ You're given strings J representing the types of stones that are jewels, and S representing the stones you have.
+ Each character in S is a type of stone you have.  You want to know how many of the stones you have are also jewels.
+ The letters in J are guaranteed distinct, and all characters in J and S are letters.
+ Letters are case sensitive, so "a" is considered a different type of stone from "A".
+
+ Example 1:
+ Input: J = "aA", S = "aAAbbbb"
+ Output: 3
+
+ Example 2:
+ Input: J = "z", S = "ZZ"
+ Output: 0
+
+ Note:
+ S and J will consist of letters and have length at most 50.
+ The characters in J are distinct.
+ */
+
+public class _771 {
+  public static class Solution1 {
+    public int numJewelsInStones(String J, String S) {
+      Set<Character> set = new HashSet<>();
+      for (char c : J.toCharArray()) {
+        set.add(c);
+      }
+      int count = 0;
+      for (char c : S.toCharArray()) {
+        if (set.contains(c)) {
+          count++;
+        }
+      }
+      return count;
+    }
+  }
+}

Diff for: src/test/java/com/fishercoder/_771Test.java

@@ -0,0 +1,21 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._771;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _771Test {
+  private static _771.Solution1 solution1;
+
+  @BeforeClass
+  public static void setup() {
+    solution1 = new _771.Solution1();
+  }
+
+  @Test
+  public void test1() {
+    assertEquals(3, solution1.numJewelsInStones("aA", "aAAbbbb"));
+  }
+}