1339:分裂二叉树的最大乘积
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轩辕龙儿
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//<p>给你一棵二叉树，它的根为 <code>root</code> 。请你删除 1 条边，使二叉树分裂成两棵子树，且它们子树和的乘积尽可能大。</p>
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//
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//<p>由于答案可能会很大，请你将结果对 10^9 + 7 取模后再返回。</p>
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//
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//<p> </p>
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//
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//<p><strong>示例 1：</strong></p>
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//
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//<p><strong><img alt="" src="https://assets.leetcode-cn.com/aliyun-lc-upload/uploads/2020/02/02/sample_1_1699.png" style="height: 200px; width: 495px;"></strong></p>
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//
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//<pre><strong>输入：</strong>root = [1,2,3,4,5,6]
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//<strong>输出：</strong>110
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//<strong>解释：</strong>删除红色的边，得到 2 棵子树，和分别为 11 和 10 。它们的乘积是 110 （11*10）
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//</pre>
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//
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//<p><strong>示例 2：</strong></p>
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//
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//<p><img alt="" src="https://assets.leetcode-cn.com/aliyun-lc-upload/uploads/2020/02/02/sample_2_1699.png" style="height: 200px; width: 495px;"></p>
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//
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//<pre><strong>输入：</strong>root = [1,null,2,3,4,null,null,5,6]
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//<strong>输出：</strong>90
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//<strong>解释：</strong>移除红色的边，得到 2 棵子树，和分别是 15 和 6 。它们的乘积为 90 （15*6）
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//</pre>
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//
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//<p><strong>示例 3：</strong></p>
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//
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//<pre><strong>输入：</strong>root = [2,3,9,10,7,8,6,5,4,11,1]
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//<strong>输出：</strong>1025
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//</pre>
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//
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//<p><strong>示例 4：</strong></p>
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//
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//<pre><strong>输入：</strong>root = [1,1]
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//<strong>输出：</strong>1
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//</pre>
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//
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//<p> </p>
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//
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//<p><strong>提示：</strong></p>
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//
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//<ul>
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// <li>每棵树最多有 <code>50000</code> 个节点，且至少有 <code>2</code> 个节点。</li>
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// <li>每个节点的值在 <code>[1, 10000]</code> 之间。</li>
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//</ul>
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//<div><div>Related Topics</div><div><li>树</li><li>深度优先搜索</li><li>二叉树</li></div></div><br><div><li>👍 72</li><li>👎 0</li></div>
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package leetcode.editor.cn;
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import com.code.leet.entiy.TreeNode;
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import java.util.HashMap;
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import java.util.Map;
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// 1339:分裂二叉树的最大乘积
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public class MaximumProductOfSplittedBinaryTree {
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public static void main(String[] args) {
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Solution solution = new MaximumProductOfSplittedBinaryTree().new Solution();
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// TO TEST
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}
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//leetcode submit region begin(Prohibit modification and deletion)
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/**
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* Definition for a binary tree node.
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* public class TreeNode {
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* int val;
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* TreeNode left;
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* TreeNode right;
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* TreeNode() {}
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* TreeNode(int val) { this.val = val; }
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* TreeNode(int val, TreeNode left, TreeNode right) {
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* this.val = val;
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* this.left = left;
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* this.right = right;
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* }
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* }
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*/
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class Solution {
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public int maxProduct(TreeNode root) {
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map = new HashMap<>();
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getSums(root);
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dfs(root, map.get(root));
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return (int) (max % 1000000007);
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}
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Map<TreeNode, Integer> map;
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long max = 0;
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private int getSums(TreeNode node) {
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if (node == null) {
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return 0;
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}
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int sum = node.val;
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if (node.left != null) {
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sum += getSums(node.left);
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}
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if (node.right != null) {
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sum += getSums(node.right);
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}
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map.put(node, sum);
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return sum;
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}
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private void dfs(TreeNode node, int sum) {
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if (node == null) {
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return;
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}
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if (node.left != null) {
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int num1 = map.get(node.left);
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max = Math.max(max, (long) num1 * (sum - num1));
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dfs(node.left, sum);
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}
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if (node.right != null) {
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int num1 = map.get(node.right);
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max = Math.max(max, (long) num1 * (sum - num1));
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dfs(node.right, sum);
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}
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}
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}
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//leetcode submit region end(Prohibit modification and deletion)
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}
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@ -0,0 +1,45 @@
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<p>给你一棵二叉树，它的根为 <code>root</code> 。请你删除 1 条边，使二叉树分裂成两棵子树，且它们子树和的乘积尽可能大。</p>
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<p>由于答案可能会很大，请你将结果对 10^9 + 7 取模后再返回。</p>
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<p> </p>
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<p><strong>示例 1：</strong></p>
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<p><strong><img alt="" src="https://assets.leetcode-cn.com/aliyun-lc-upload/uploads/2020/02/02/sample_1_1699.png" style="height: 200px; width: 495px;"></strong></p>
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<pre><strong>输入：</strong>root = [1,2,3,4,5,6]
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<strong>输出：</strong>110
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<strong>解释：</strong>删除红色的边，得到 2 棵子树，和分别为 11 和 10 。它们的乘积是 110 （11*10）
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</pre>
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<p><strong>示例 2：</strong></p>
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<p><img alt="" src="https://assets.leetcode-cn.com/aliyun-lc-upload/uploads/2020/02/02/sample_2_1699.png" style="height: 200px; width: 495px;"></p>
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<pre><strong>输入：</strong>root = [1,null,2,3,4,null,null,5,6]
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<strong>输出：</strong>90
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<strong>解释：</strong>移除红色的边，得到 2 棵子树，和分别是 15 和 6 。它们的乘积为 90 （15*6）
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</pre>
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<p><strong>示例 3：</strong></p>
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<pre><strong>输入：</strong>root = [2,3,9,10,7,8,6,5,4,11,1]
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<strong>输出：</strong>1025
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</pre>
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<p><strong>示例 4：</strong></p>
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<pre><strong>输入：</strong>root = [1,1]
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<strong>输出：</strong>1
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</pre>
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<p> </p>
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<p><strong>提示：</strong></p>
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<ul>
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<li>每棵树最多有 <code>50000</code> 个节点，且至少有 <code>2</code> 个节点。</li>
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<li>每个节点的值在 <code>[1, 10000]</code> 之间。</li>
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</ul>
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<div><div>Related Topics</div><div><li>树</li><li>深度优先搜索</li><li>二叉树</li></div></div><br><div><li>👍 72</li><li>👎 0</li></div>
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