[英]Counting the inner nodes (parent nodes) in a binary tree recursively
I need to create a recursive method that takes as a parameter the root node of a binary search tree. 我需要创建一个以二进制搜索树的根节点为参数的递归方法。 This recursive method will then return the int value of the total number of inner nodes in the entire binary search tree. 然后,此递归方法将返回整个二进制搜索树中内部节点总数的int值。
This is what I have so far: 这是我到目前为止的内容:
int countNrOfInnerNodes (Node node) {
if(node == null) {
return 0;
}
if (node.left != null && node.right != null){
return 1;
}
return countNrOfInnerNodes(node.left)+countNrOfInnerNodes(node.right)
}
}
Is there a better way? 有没有更好的办法? I also stuck to find a iterativ solution. 我还坚持寻找iterativ解决方案。
Here's the recursive method fixed: 这是固定的递归方法:
int countNrOfInnerNodes (Node node) {
if(node == null) {
return 0;
}
if (node.left == null && node.right == null) {
// not an inner node !
return 0;
} else {
// the number of inner nodes in the left sub-tree + the number of inner
// nodes in the right sub-tree, plus 1 for this inner node
return countNrOfInnerNodes(node.left) + countNrOfInnerNodes(node.right) + 1;
}
}
Here's the iterative method: 这是迭代方法:
int countNrOfInnerNodes(Node node) {
if (node == null)
return 0;
Stack<Node> nodesToCheck = new Stack<Node>();
nodesToCheck.push(node);
int count = 0;
while (!nodesToCheck.isEmpty()) {
Node checkedNode = nodesToCheck.pop();
boolean isInnerNode = false;
if (node.left != null) {
isInnerNode = true;
nodesToCheck.push(node.left);
}
if (node.right != null) {
isInnerNode = true;
nodesToCheck.push(node.right);
}
if (isInnerNode)
count++;
}
return count;
}
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