Create 771-jewels-and-stones.js

Author: everthis

771-jewels-and-stones.js

@@ -0,0 +1,14 @@
+/**
+ * @param {string} J
+ * @param {string} S
+ * @return {number}
+ */
+const numJewelsInStones = function(J, S) {
+  if(J == null || J === '' || S == null || S === '') return 0
+  const m = new Set(J)
+  let res = 0
+  for(let e of S) {
+    if(m.has(e)) res++
+  }
+  return res
+};