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flatten-binary-tree-to-linked-list.dart (898B)

      1 //Given a binary tree the values after performing a preorder
      2 //traversal and then reorganizing the tree so that the preorder
      3 //values are all placed on the right side similar to a linked list.
      4 //To do this I iterated through the tree adding each node to the list
      5 //as I went (pre-order). I then created a new binary tree reusing the root
      6 //where each right value was the next value in the list.
      7 //Time: 285ms Beats: 100%
      8 //Memory: 143.8MB Beats: 50%
      9 
     10 class Solution {
     11   List<int> vals = [];
     12   void flatten(TreeNode? root) {
     13       recurse(root);
     14       root?.left = null;
     15       TreeNode? itr = root;
     16       for(int i = 1 ; i < vals.length ; ++i){
     17           itr?.right = new TreeNode(vals[i]);
     18           itr = itr?.right;
     19       }
     20 
     21   }
     22   void recurse(TreeNode? root){
     23       if(root == null){
     24           return;
     25       }
     26       vals.add(root.val);
     27       recurse(root.left);
     28       recurse(root.right);
     29   }
     30 }