判断一个树是否是另一个树的子树

判断一个树是否是另一个树的子树

package ZHIHU;

public class Main20171009004 {

/**
* 判断一个树是否是另一个树的子树
*/
private static class Node{
int value;
Node left, right;
Node(int value){
this.value = value;
left =null;
right = null;
}
}

private static boolean isSubTree(Node root1, Node root2){
boolean ans = false;
if(root1 != null && root2 != null){
if(root1.value == root2.value){
ans = isSub(root1, root2);
}else{
ans = isSubTree(root1.left, root2);
if(!ans){
ans = isSubTree(root1.right, root2);
}
}
}
return ans;
}

//
private static boolean isSub(Node root1, Node root2){
if(root2 == null){
return true;
}
if(root1 == null){
return false;
}
if(root1.value != root2.value)
return false;

return isSub(root1.left, root2.left) && isSub(root1.right, root2.right);
}

public static void main(String[] args) {

Node root1 = new Node(1);
Node node1 = new Node(2);
Node node2 = new Node(2);
root1.left = node1;
root1.right = node2;
Node node3 = new Node(3);
Node node4 = new Node(4);
Node node5 = new Node(3);
root1.left.left = node3;
root1.left.right = node4;
root1.right.left = node5;
Node node6 = new Node(2);
root1.left.right.left = node6;

Node root2 = new Node(2);
Node node7 = new Node(3);
Node node8 = new Node(4);
root2.left = node7;
root2.right = node8;

System.out.println(isSubTree(root1, root2));

}

}