Question

我正在创建一个二进制搜索树项目，其中一个问题是创建2棵树并检查它们是否相等。当我实现该方法时，我不断 firstTree和secondTree相等。以下是相关代码：

BstTest2 firstTree = new BstTest2();
firstTree.addNode(50, "Francisco Domingo Carlos Andres Sebastián d'Anconia");
firstTree.addNode(25, "John Galt");
firstTree.addNode(15, "Hugh Akston");
firstTree.addNode(30, "Ragnar Danneskjöld");
firstTree.addNode(85, "Hank Reardan"); //implementing add method

BstTest2 secondTree = new BstTest2();
secondTree.addNode(50, "Francisco Domingo Carlos Andres Sebastián d'Anconia");
secondTree.addNode(25, "John Galt");
secondTree.addNode(15, "Hugh Akston");
secondTree.addNode(30, "Ragnar Danneskjöld");
secondTree.addNode(75, "Midas Mulligan");
secondTree.addNode(85, "Hank Reardan");

if(firstTree.isEqual(secondTree))
{
     System.out.println("firstTree and secondTree are equal");
}
else
{
     System.out.println("firstTree and secondTree are not equal");
}

isEqual和用于比较树的检查方法

public boolean isEqual(BstTest2 tree1)
{
    return check(this.rootNode, tree1.rootNode);
}
public boolean check(Node node1, Node node2)
{
    if((node1 == null) && (node2 == null))
    {
        return true;
    } 
    else if((node1 == null) || node2 != null)
    {
        return false;
    } 
    else if((node1 != null) || node2 == null)
    {
        return false;
    } 
    else
    {
        return check(node1.leftChild, node2.leftChild) && check(node1.rightChild, node2.rightChild);
    }
}

当树不相等时，我不断获取“ firstTree和secondTree相等”的isEqual（）和check（）方法怎么办？

Answer 1

您忘记检查node1和node2的值是否相同。

如果它们不相同，则表示这两棵树不相同。
如果它们相同，我们将继续检查它们的左孩子和右孩子是否相同。


public boolean check(Node node1, Node node2)
{
    if((node1 == null) && (node2 == null))
    {
        return true;
    } 

    // If only one node is null, it means these two trees are not the same
    // These two nodes here couldn't both be null because we check this condition earlier.
    if(node1 == null || node2 == null)
    {
        return false;
    } 

    // Check if the value of node1 and node2 are the same
    if(node1.val != node2.val)
    {
        return false;
    } 

    return check(node1.leftChild, node2.leftChild) && check(node1.rightChild, node2.rightChild);
}

检查2个二叉搜索树是否相等

1 个答案: