1339. Maximum Product of Splitted Binary Tree

sol.java

class Solution {
    int module = (int) Math.pow(10,9)+7;
    public int maxProduct(TreeNode root) {
        List<Long> sum = new ArrayList<>();
        long total = getTotalSum(root,sum);
        int max = 0;
        for (Long target : sum) {
            long t = (target * (total - target);
            max = Math.max(max,t);
        }
        return (int) (max%module);
    }

    public long getTotalSum(TreeNode node, List<Long> sum){
        if(node == null) return 0;
        long left = getTotalSum(node.left,sum);
        long right = getTotalSum(node.right,sum);
        long total = (left + right)%module;
        sum.add(total);
        return total;
    }
}