Given a binary search tree and the lowest and highest boundaries as L and R, trim the tree so that all its elements lies in [L, R] (R >= L). You might need to change the root of the tree, so the result should return the new root of the trimmed binary search tree.
Example 1:
Input:
1
/ 0 2
L = 1
R = 2
Output:
1
2
Example 2:
Input:
3
/ 0 4
2
/
1
L = 1
R = 3
Output:
3
/
2
/
1
1 public TreeNode trimBST(TreeNode root, int L, int R) { 2 if(root == null){ 3 return null; 4 }else if(root.val >= L && root.val <= R){ 5 root.left = trimBST(root.left, L, R); 6 root.right = trimBST(root.right, L, R); 7 return root; 8 }else if(root.val < L){ 9 return trimBST(root.right, L, R); 10 }else if(root.val > R){ 11 return trimBST(root.left, L, R); 12 } 13 return null; 14 }
原文：http://www.cnblogs.com/luckygxf/p/7750490.html