Create 137-single-number-ii.js

Author: everthis

137-single-number-ii.js

@@ -0,0 +1,15 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+const singleNumber = function(nums) {
+    const hash = {}
+    
+    nums.forEach(el => {
+      hash[el] = (hash[el] && hash[el] + 1) || 1
+    })
+    
+    for(let el in hash) {
+      if(hash[el] === 1) return +el
+    }
+};