Create 2471-minimum-number-of-operations-to-sort-a-binary-tree-by-level.js

Author: everthis

2471-minimum-number-of-operations-to-sort-a-binary-tree-by-level.js

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+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number}
+ */
+var minimumOperations = function(root) {
+  let res = 0
+  let q = []
+  q.push(root)
+  
+  while(q.length) {
+    const nxt = []
+    res += minSwaps(q.map(e =>  e.val), q.length)    
+    const len = q.length
+    
+    for(let i = 0; i < len; i++) {
+      const cur = q[i]
+      if(cur.left) nxt.push(cur.left)
+      if(cur.right) nxt.push(cur.right)
+    }
+
+    q = nxt
+  }
+  
+  
+  return res
+};
+
+function swap(arr, i, j)
+{
+  let temp = arr[i];
+  arr[i] = arr[j];
+  arr[j] = temp;
+}
+ 
+// Return the minimum number
+// of swaps required to sort
+// the array
+function minSwaps(arr,N)
+{
+  let ans = 0;
+  let temp = arr.slice();
+ 
+  // Hashmap which stores the
+  // indexes of the input array
+  let h = new Map();
+ 
+  temp.sort((a, b) => a - b);
+  for (let i = 0; i < N; i++)
+  {
+    h.set(arr[i], i);
+  }
+  for (let i = 0; i < N; i++)
+  {
+   
+    // This is checking whether
+    // the current element is
+    // at the right place or not
+    if (arr[i] != temp[i])
+    {
+      ans++;
+      let init = arr[i];
+ 
+      // If not, swap this element
+      // with the index of the
+      // element which should come here
+      swap(arr, i, h.get(temp[i]));
+ 
+      // Update the indexes in
+      // the hashmap accordingly
+      h.set(init,h.get(temp[i]));
+      h.set(temp[i],i);
+    }
+  }
+  // console.log(arr, ans)
+  return ans;
+}