106 lines
3.6 KiB
Java
106 lines
3.6 KiB
Java
//<p>给你一棵以节点 0 为根节点的树，定义如下：</p>
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//
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//<ul>
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// <li>节点的总数为 <code>nodes</code> 个；</li>
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// <li>第 <code>i</code> 个节点的值为 <code>value[i]</code> ；</li>
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// <li>第 <code>i</code> 个节点的父节点是 <code>parent[i]</code> 。</li>
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//</ul>
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//
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//<p>请你删除节点值之和为 0 的每一棵子树。</p>
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//
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//<p>在完成所有删除之后，返回树中剩余节点的数目。</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><img alt="" src="https://assets.leetcode-cn.com/aliyun-lc-upload/uploads/2019/11/30/1421_sample_1.png" style="height: 347px; width: 403px;"></p>
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//
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//<pre><strong>输入：</strong>nodes = 7, parent = [-1,0,0,1,2,2,2], value = [1,-2,4,0,-2,-1,-1]
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//<strong>输出：</strong>2
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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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//<pre><strong>输入：</strong>nodes = 7, parent = [-1,0,0,1,2,2,2], value = [1,-2,4,0,-2,-1,-2]
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//<strong>输出：</strong>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>nodes = 5, parent = [-1,0,1,0,0], value = [-672,441,18,728,378]
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//<strong>输出：</strong>5
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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>nodes = 5, parent = [-1,0,0,1,1], value = [-686,-842,616,-739,-746]
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//<strong>输出：</strong>5
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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><code>1 <= nodes <= 10^4</code></li>
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// <li><code>parent.length == nodes</code></li>
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// <li><code>0 <= parent[i] <= nodes - 1</code></li>
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// <li><code>parent[0] == -1</code> 表示节点 <code>0</code> 是树的根。</li>
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// <li><code>value.length == nodes</code></li>
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// <li><code>-10^5 <= value[i] <= 10^5</code></li>
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// <li>题目输入数据 <strong>保证</strong> 是一棵 <strong>有效的树</strong> 。</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>广度优先搜索</li></div></div><br><div><li>👍 32</li><li>👎 0</li></div>
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package leetcode.editor.cn;
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import java.util.ArrayList;
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import java.util.List;
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// 1273:删除树节点
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public class DeleteTreeNodes {
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public static void main(String[] args) {
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Solution solution = new DeleteTreeNodes().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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class Solution {
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public int deleteTreeNodes(int nodes, int[] parent, int[] value) {
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List<List<Integer>> lists = new ArrayList<>();
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for (int i = 0; i < nodes; i++) {
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lists.add(new ArrayList<>());
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}
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int head = 0;
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for (int i = 0; i < parent.length; i++) {
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if (parent[i] == -1) {
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head = i;
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continue;
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}
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lists.get(parent[i]).add(i);
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}
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int[] tmp = dfs(lists, head, value);
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return tmp[0] == 0 ? 0 : tmp[1];
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}
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private int[] dfs(List<List<Integer>> lists, int index, int[] value) {
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int[] cur = new int[]{value[index], 1};
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List<Integer> list = lists.get(index);
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int size = list.size();
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if (size == 0) {
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return cur;
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}
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for (Integer indx : list) {
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int[] tmp = dfs(lists, indx, value);
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if (tmp[0] != 0) {
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cur[0] += tmp[0];
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cur[1] += tmp[1];
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}
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}
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return cur;
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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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