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

Author: everthis

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

@@ -0,0 +1,25 @@
+/**
+ * @param {number[]} changed
+ * @return {number[]}
+ */
+ const findOriginalArray = function(changed) {
+  const n = changed.length, res = []
+  if(n % 2 === 1 || n === 0) return res
+  const hash = {}
+  for(let e of changed) {
+    if(hash[e] == null) hash[e] = 0
+    hash[e]++
+  }
+  changed.sort((a, b) => a - b)
+
+  for(let i = 0, len = n; i < len; i++) {
+    const cur = changed[i], dVal = cur * 2
+    if (cur === 0 && hash[cur] % 2 === 1) continue
+    if(hash[dVal] && hash[cur]) {
+      res.push(cur)
+      hash[dVal]--
+      hash[cur]--
+    }
+  }
+  return res.length === n / 2 ? res : []
+};