在訂單意味着你首先要遍歷樹的左側部分,所以:
TreeNode tree // this is your tree you want to traverse
E[] array = new E[tree.size]; // the arrays length must be equivalent to the number of Nodes in the tree
int index = 0; // when adding something to the array we need an index
inOrder(tree, array, index); // thats the call for the method you'll create
的方法本身可能看起來是這樣的:
public void inOrder(TreeNode node, E[] array, int index){
if(node == null){ // recursion anchor: when the node is null an empty leaf was reached (doesn't matter if it is left or right, just end the method call
return;
}
inOrder(node.getLeft(), array, index); // first do every left child tree
array[index++]= node.getData(); // then write the data in the array
inOrder(node.getRight(), array, index); // do the same with the right child
}
有點像這樣。我只是不確定索引和它需要增加的地方。如果您不想擔心索引,或者您不知道樹中有多少個節點,則可以使用ArrayList,最後將其轉換爲數組。
通常清潔呼叫的方法是建立一個圍繞這樣的遞歸方法:
public E[] inOrderSort(TreeNode tree){
E[] array = new E[tree.size];
inOrder(tree, array, 0);
return array;
}