Update 2007-find-original-array-from-doubled-array.js

Author: everthis

2007-find-original-array-from-doubled-array.js

@@ -1,3 +1,31 @@
+/**
+ * @param {number[]} changed
+ * @return {number[]}
+ */
+ const findOriginalArray = function(changed) {
+  const n = changed.length, res = [], { abs } = Math
+  if(n % 2 === 1 || n === 0) return res
+  const hash = {}
+  for(let e of changed) {
+    if(hash[e] == null) hash[e] = 0
+    hash[e]++
+  }
+  const keys = Object.keys(hash)
+  keys.sort((a, b) => abs(a) - abs(b))
+
+  for(let k of keys) {
+    if(hash[k] > (hash[k * 2] || 0)) return []
+    for(let i = 0; i < hash[k]; i++) {
+      res.push(k)
+      hash[2 * k]--
+    }
+  }
+
+  return res
+};
+
+// another
+
 /**
  * @param {number[]} changed
  * @return {number[]}