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.

Note:

• Both of the given trees will have between 1 and 100 nodes.

题目：二叉树的叶子结点形成一个序列，判断给定的两颗二叉树这样的序列是否相等

思路：vector leafSequence（TreeNode* root）函数将二叉树的叶子结点形成序列。形成序列的时候是采用递归的方式，如果根节点是叶子结点，则push_back进入，再依次递归左子树、右子树。这样将两个二叉树转换为vector之后，直接return vec1==vec2，就是我们要的结果了。

代码如下：

class Solution {
public:
    bool leafSimilar(TreeNode* root1, TreeNode* root2) {
        vector vec1;
		vec1 = leafSequence(root1);
        vector vec2;
		vec2 = leafSequence(root2);
        return vec1==vec2;
    }
    vector leafSequence(TreeNode* root){
    	vector ret;
    	if(!root)
    		return ret;
    	if(root){
    		if(root->left==NULL&&root->right==NULL)
    			ret.push_back(root->val);
    		vector left = leafSequence(root->left);
    		ret.insert(ret.end(),left.begin(),left.end());
			vector right = leafSequence(root->right);	
    		ret.insert(ret.end(),right.begin(),right.end());
		}
		return ret;
	}
};

AC，beats 100%