【剑指offer-Java版】18树的子结构

public class _Q18 {

public boolean HasSubTree(BinaryTreeNode tree1, BinaryTreeNode tree2) {
if (tree1 == null) return false;
if (tree2 == null) return true; // 对于一棵空的树，默认是任何非空树都是包含空树的

boolean result = false;
if (tree1.value == tree2.value) {
result = DoesTree1HasTree2(tree1, tree2);
}
if (!result) { // 如果没找到就在左子树中寻找
result = HasSubTree(tree1.leftChild, tree2);
}
if (!result) { // 如果仍然没有找到就在右子树中寻找
result = HasSubTree(tree1.rightChild, tree2);
}

return result;
}

private boolean DoesTree1HasTree2(BinaryTreeNode tree1, BinaryTreeNode tree2){
if(tree2 == null) return true;
if(tree1 == null) return false;

boolean result = false;
if(tree1.value != tree2.value){
return false;
}else{
result = DoesTree1HasTree2(tree1.leftChild, tree2.leftChild)
&& DoesTree1HasTree2(tree1.rightChild, tree2.rightChild);
}

return result;
}
}

public class _Q18Test extends TestCase {

_Q18 subTree = new _Q18();

public void test(){
BinaryTreeNode node0 = new BinaryTreeNode();
BinaryTreeNode node1 = new BinaryTreeNode();
BinaryTreeNode node2 = new BinaryTreeNode();
BinaryTreeNode node3 = new BinaryTreeNode();
BinaryTreeNode node4 = new BinaryTreeNode();
BinaryTreeNode node5 = new BinaryTreeNode();
BinaryTreeNode node6 = new BinaryTreeNode();

BinaryTreeNode node7 = new BinaryTreeNode();
BinaryTreeNode node8 = new BinaryTreeNode();
BinaryTreeNode node9 = new BinaryTreeNode();

node0.value = 8;
node1.value = 8;
node2.value = 7;
node3.value = 9;
node4.value = 2;
node5.value = 4;
node6.value = 7;

node7.value = 8;
node8.value = 9;
node9.value = 2; // 改动以修改成一棵不在tree1中的子树

node0.leftChild = node1;
node0.rightChild = node2;
node1.leftChild = node3;
node1.rightChild = node4;
node4.leftChild = node5;
node4.rightChild = node6;

node2.leftChild = null; node2.rightChild = null;
node3.leftChild = null; node3.rightChild = null;
node5.leftChild = null; node5.rightChild = null;
node6.leftChild = null; node6.rightChild = null;

node7.leftChild = node8;
node7.rightChild = node9;

node8.leftChild = null; node8.rightChild = null;
node9.leftChild = null; node9.rightChild = null;

System.out.println(subTree.HasSubTree(null, node7));
}
}