Problem

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

      2
    /   \
   5     1
  / \   / \
 6   2 9   8
    / \
   7   4

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.

Pre analysis

A simple walk over tree with pre order should give leaf, and if both array are same then it is leaf-similar tree.

Post analysis

Need to learn in-order, pre-order, post-order traversal #todo

Another solution

Another JS specific better solution

var leafSimilar = function(root1, root2) {
    return helper(root1)===helper(root2);
};


var helper=function(root){
    var op=[];
    inorder(root,op);
    return op.join(",");
}

var inorder=function(root,op){
    if(!root){
        return;
    }
    if(!root.left && !root.right){
        op.push(root.val);
    }
    inorder(root.left,op);
    inorder(root.right,op);
}