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.
/**
* 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;
}
}