題目描述
輸入兩棵二叉樹A,B,判斷B是不是A的子結構。(ps:我們約定空樹不是任意一個樹的子結構)
思路:將B與A,A的左子樹,A的右子樹分別進行判斷,如果元素不相等返回 false ,運用遞歸直到A子樹爲空此時返回 false
/**
public class TreeNode {
int val = 0;
TreeNode left = null;
TreeNode right = null;
public TreeNode(int val) {
this.val = val;
}
}
*/
public class Solution {
public boolean HasSubtree(TreeNode root1,TreeNode root2) {
if(root1 == null || root2 == null)return false;
return isHubTree(root1,root2)||HasSubtree(root1.right,root2)||HasSubtree(root1.left,root2);
}
public boolean isHubTree(TreeNode root1,TreeNode root2){
if(root1 == null && root2 == null)return true;
if(root1 == null)return false;
if(root2 == null)return true;
if(root1.val != root2.val)return false;
return isHubTree(root1.left,root2.left) && isHubTree(root1.right,root2.right);
}
}