As the title says, I have to trim a binary tree based on a given min and max value. Each node stores a value, and a left/right node. I may define private helper methods to solve this problem, but otherwise I may not call any other methods of the class nor create any data structures such as arrays, lists, etc.

An example would look like this:

                           overallRoot
                         _____[50]____________________
                        /                             \
          __________[38]                _______________[90]
         /              \              /
    _[14]                [42]      [54]_____
   /     \                                  \
[8]       [20]                               [72]
          \                             /    \
               [26]                     [61]      [83]

trim(52, 65);

should return:

overallRoot
[54]
    \
     [61]

My attempted solution has three methods:

public void trim(int min, int max) {
rootFinder(overallRoot, min, max);

}

First recursive method finds the new root perfectly.

private void rootFinder(IntTreeNode node, int min, int max) {
if (node == null)
    return;

if (overallRoot.data < min) {
    node = overallRoot = node.right;
    rootFinder(node, min, max);

}

else if (overallRoot.data > max) {
    node = overallRoot = node.left;
    rootFinder(node, min, max);
}
else
    cutter(overallRoot, min, max);
}

This second method should eliminate any further nodes not within the min/max, but it doesn't work as I would hope.

private void cutter(IntTreeNode node, int min, int max) {
if (node == null)
    return;

if (node.data <= min) {
    node.left = null;
}
if (node.data >= max) {
    node.right = null;
}

if (node.data < min) {
    node = node.right;
}

if (node.data > max) {
    node = node.left;
}


cutter(node.left, min, max);
cutter(node.right, min, max);
}

This returns:

overallRoot
[54]_____
         \
          [72]
         /
     [61]

Any help is appreciated. Feel free to ask for further explanation as needed.