Maximum Product of Splitted Binary Tree
给一个二叉树, 通过断其中一个edge, 求断后两个子树的值的和的乘积最大. 这个题我开始的时候, 是扫了两边做的, 后来发现用一个set可以直接扫一次, set中装满所有的子树和…好吧…test cases不是那么紧.
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/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ class Solution { public int maxProduct(TreeNode root) { Set<Integer> sums = new HashSet<>(); int total = find(root, sums); long max = 0; for (long sum : sums) { max = Math.max(max, sum * (total - sum)); } return (int) (max % (1e9+7)); } public int find(TreeNode root, Set<Integer> sums) { if (root == null) return 0; int sum = find(root.left, sums) + find(root.right, sums) + root.val; sums.add(sum); return sum; } } |