【树】572. 另一个树的子树
作者:互联网
题目:
解法:
方法一:先序遍历
1 class Solution { 2 public boolean isSubtree(TreeNode s, TreeNode t) { 3 String tree1 = preOrder(s, true); 4 String tree2 = preOrder(t, true); 5 return tree1.indexOf(tree2) >= 0; 6 } 7 8 private String preOrder(TreeNode node, boolean left) { 9 if (node == null) { 10 if (left) return "lnull"; 11 else return "rnull"; 12 } 13 14 return "#" + node.val + " " + preOrder(node.left, true) + " " + preOrder(node.right, false); 15 } 16 }
方法二:比较节点
1 class Solution { 2 public boolean isSubtree(TreeNode s, TreeNode t) { 3 return traverse(s, t); 4 } 5 6 private boolean traverse(TreeNode s, TreeNode t) { 7 return s != null && (equals(s, t) || traverse(s.left, t) || traverse(s.right, t)); 8 } 9 10 // 比较两棵树是否相等 11 private boolean equals(TreeNode t1, TreeNode t2) { 12 if (t1 == null && t2 == null) return true; 13 else if (t1 == null || t2 == null) return false; 14 15 return t1.val == t2.val && equals(t1.left, t2.left) && equals(t1.right, t2.right); 16 } 17 }
标签:子树,TreeNode,一个,572,t2,t1,return,null,left 来源: https://www.cnblogs.com/ocpc/p/12821743.html