digitTreeSum

We're going to store numbers in a tree. Each node in this tree will store a single digit (from 0 to 9), and each path from root to leaf encodes a non-negative integer.

Given a binary tree t, find the sum of all the numbers encoded in it.

Link for the problem - https://app.codesignal.com/interview-practice/question/2oxNWXTS8eWBzvnRB/description

ArrayList<Long> list;
long solution(Tree<Integer> t) {

    list = new ArrayList<>();
    dfs(t, 0);
    long sum = 0l;
    for(int i=0; i<list.size(); i++) {
        sum += (long)list.get(i);
    }
    return sum;
}

void dfs(Tree<Integer> root, long currSum) {

    if(root==null)
        return;

    currSum = currSum*10 + root.value; 

    if(root.left==null && root.right==null) {
        list.add(currSum);
    }

    if(root.left!=null)
        dfs(root.left, currSum);
    if(root.right!=null)
        dfs(root.right, currSum);

    currSum = currSum/10;
    return;

}