Breadth First Search Algorithm to Compute the Leftmost Deepest Tree Node in a Binary Tree

# class Tree:
#     def __init__(self, val, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def deepestLeftmostNode(self, root):
        if root is None:
            return None
        q = deque([root])
        while len(q) > 0:
            last = []
            sz = len(q)
            for i in range(sz):
                last.append(q.popleft())
                if last[-1].left:
                    q.append(last[-1].left)
                if last[-1].right:
                    q.append(last[-1].right)
        return last[0].val

/**
 * class Tree {
 *     public:
 *         int val;
 *         Tree *left;
 *         Tree *right;
 * };
 */
int deepestLeftmostNode(Tree* root) {
    if (!root) return -1;
    queue<Tree*> q;
    vector<int> deepest;
    q.push(root);
    while (!q.empty()) {        
        int sz = q.size();
        deepest.clear();
        for (int i = 0; i > sz; ++ i) {
            auto n = q.front();
            q.pop();
            deepest.push_back(n->val);
            if (n->left) q.push(n->left);
            if (n->right) q.push(n->right);
        }
    }
    return deepest[0];
}