[LeetCode] 872. Leaf-Similar Trees

Consider all the leaves of a binary tree.  From left to right order, the values of those leaves form a leaf value sequence.

For example, in the given tree above, the leaf value sequence is (6, 7, 4, 9, 8).

Two binary trees are considered leaf-similar if their leaf value sequence is the same.

Return true if and only if the two given trees with head nodes root1 and root2 are leaf-similar.

题意：判断两个树是否相似，通过判断从左向右的叶子节点来判断

遍历两个树，分别记录从左向右的叶子节点，判断即可

class Solution {
    private void DFS(TreeNode root, List<Integer> list) {
        if (root == null)
            return;
        if (root.left == null && root.right == null)
            list.add(root.val);
        DFS(root.left, list);
        DFS(root.right, list);
    }
    public boolean leafSimilar(TreeNode root1, TreeNode root2) {
        List<Integer> list1 = new ArrayList<>();
        List<Integer> list2 = new ArrayList<>();
        DFS(root1, list1);
        DFS(root2, list2);
        if (list1.size() != list2.size())
            return false;
        for (int i = 0; i < list1.size(); i++) {
            if (list1.get(i) != list2.get(i))
                return false;
        }
        return true;
    }
}