Breadth First Search Algorithm to Compute the Sum of the Deepest Nodes

/**
 * class Tree {
 *     public:
 *         int val;
 *         Tree *left;
 *         Tree *right;
 * };
 */
int computeLevelOfDeepstNodes(Tree* root) {
    if (!root) {
        return 0;
    }
    int sum = 0;
    queue<Tree*> q;
    q.push(root);
    while (!q.empty()) {
        auto sz = q.size();
        sum = 0;
        for (int i = 0; i < sz; ++ i) {
            auto p = q.front();
            q.pop();
            if (p->left) q.push(p->left);
            if (p->right) q.push(p->right);
            sum += p->val;
        }
    }
    return sum;
}

# class Tree:
#     def __init__(self, val, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def solve(self, root):
        if root is None:
            return 0
        q = deque([root])
        lastSum = 0
        while len(q) > 0:
            sz = len(q)
            lastSum = 0
            for _ in range(sz):
                x = q.popleft()
                lastSum += x.val
                if x.left:
                    q.append(x.left)
                if x.right:
                    q.append(x.right)
        return lastSum