Create 1743-restore-the-array-from-adjacent-pairs.js

Author: everthis

1743-restore-the-array-from-adjacent-pairs.js

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+/**
+ * @param {number[][]} adjacentPairs
+ * @return {number[]}
+ */
+const restoreArray = function(pairs) {
+  const m = {}
+  for(let e of pairs) {
+    const [k, v] = e
+    if(m[k] == null) m[k] = new Set()
+    if(m[v] == null) m[v] = new Set()
+    m[k].add(v)
+    m[v].add(k)
+  }
+  const q = [pairs[0]]
+  let res = pairs[0]
+  m[res[0]].delete(res[1])
+  m[res[1]].delete(res[0])
+  let n = pairs.length
+  while(n) {
+    const front = res[0], rear = res[res.length - 1]
+    
+    if(m[front]) {
+        const newf = [...m[front].values()][0]
+        if(m[front].size) res.unshift(newf)
+        if(m[front]) m[front].delete(newf)
+        if(m[newf]) m[newf].delete(front)
+        if(m[front].size === 0) delete m[front]
+    }
+     
+    if(m[rear]) {
+       const newr = [...m[rear].values()][0]
+       if(m[rear].size) res.push(newr)
+       if(m[rear]) m[rear].delete(newr)
+       if(m[newr]) m[newr].delete(rear)
+       if(m[rear].size === 0) delete m[rear]
+    }
+    n--
+  }
+    
+  return res
+};