Interviews

Move Coins

user profile image
System made a post.

Given a tree with n nodes. Each node has k coins, where 0 <= k <= n . There are total n coins on the tree.
The goal is to move the coins such that each node has exactly one coin. What's the minimum moves required?
Each move can only move one coin to an adjacent node.


    int moveCoins(TreeNode root) {
        return dfs(root, new HashMap<>());
    }

    int dfs(TreeNode n, Map count) {
        if(!count.containsKey(n)) {
            count.put(n, n.val);
        }
        int coinsNum = count.get(n);
        int res = 0;
        for(TreeNode kid : n.children) {
            res += dfs(kid, count);
            coinsNum += count.get(kid);
            res += Math.abs(count.get(kid));
        }
        count.put(n, coinsNum - 1);
        return res;
    }


One-on-One Algorithm and Coding Training

One-on-One System Design Training

One-on-One Mock Interview

Get one-to-one training from Google Facebook engineers


Top-notch Professionals

Learn from Facebook, Google, Uber senior engineers interviewed 100+ candidates.aonecode.com
Most recent interview questions and system design topics gathered from aonecode alumnus.
One-to-one online classes. Get feedbacks from real interviewers.


Customized Private Class

Already a coding expert? - Advance straight to hard interview topics of your interest.
New to the ground? - Develop basic coding skills with your own designated mentor.
Days before interview? - Focus on most important problems in target company question bank.


Free Consultation

aonecoding@gmail.com