Create 2122-recover-the-original-array.js

Author: everthis

2122-recover-the-original-array.js

@@ -0,0 +1,35 @@
+/**
+ * @param {number[]} nums
+ * @return {number[]}
+ */
+const recoverArray = function(nums) {
+  const n = nums.length, cnt = calcHash(nums)
+  nums.sort((a, b) => a - b)
+  for(let i = 1; i < n; i++) {
+    const tk = nums[i] - nums[0]
+    if(tk === 0 || tk % 2 === 1) continue
+    const [valid, res] = helper(tk)
+    if(valid) return res
+  }
+  
+  function helper(tk) {
+    const res = [], hash = Object.assign({}, cnt)
+    for(let i = 0; i < n; i++) {
+      const cur = nums[i]
+      if(hash[cur] === 0) continue
+      if(hash[cur + tk] === 0 || hash[cur + tk] == null) return [false]
+      hash[cur]--
+      hash[cur + tk]--
+      res.push(cur + tk / 2)
+    }
+    return [true, res]
+  }
+  function calcHash(arr) {
+    const hash = {}
+    for(let e of arr) {
+      if(hash[e] == null) hash[e] = 0
+      hash[e]++
+    }
+    return hash
+  }
+};