对点分隔的字符串列表进行分组

Question

将点分隔字符串分组为固定格式

在输入中，我得到了代表某种树结构的下一行的数组：

    "323-060",
    "323-060.040",
    "323-060.040.030",    
    "323-060.088",
    "323-060.088.020",    
    "323-060.010",
    "323-060.010.080",
    "323-060.010.080.020",
    "323-060.010.080.060"

它是树形结构：

“323-060”-根 这棵树有下一个层次结构

323-060   /*rot*/
        040       /*second level, full path: 323-060.040*/
            030   /* third level, full path: 323-060.040.303 */
        088
            020

因此，我必须将下一个列表分组：

"323-060\323-060.040\323-060.040.030"
"323-060\323-060.088\323-060.088.020"
"323-060\323-060.010\323-060.010.080\323-060.010.080.020"
"323-060\323-060.010\323-060.010.080\323-060.010.080.060"

如何在 Java 中做到这一点？

Answer 1

在下面的代码中，

Node

类代表树中的每个

node

。

buildTree()

方法通过用点分割每个字符串来获取部分来根据输入创建树。

HashMap

用于通过完整路径跟踪

nodes

。对于每一部分，我们检查

node

是否存在于地图中，如果不存在，我们创建一个新的。在

generatePaths()

方法中，我们递归遍历树以创建预期输出。

package org.example;

import java.util.*;

public class GroupString {
    static class Node {
        String value;
        List<Node> children;

        Node(String value) {
            this.value = value;
            this.children = new ArrayList<>();
        }
    }

    public static void main(String[] args) {
        String[] input = {
                "323-060",
                "323-060.040",
                "323-060.040.030",
                "323-060.088",
                "323-060.088.020",
                "323-060.010",
                "323-060.010.080",
                "323-060.010.080.020",
                "323-060.010.080.060"
        };

        Node root = buildTree(input);
        List<String> result = new ArrayList<>();
        generatePaths(root, new ArrayList<>(), result);

        for (String path : result) {
            System.out.println(path);
        }
    }

    private static Node buildTree(String[] input) {
        Map<String, Node> nodeMap = new HashMap<>();
        Node root = null;

        for (String path : input) {
            String[] parts = path.split("\\.");
            StringBuilder currentPath = new StringBuilder();
            Node parent = null;

            for (String part : parts) {
                if (currentPath.length() > 0) {
                    currentPath.append(".");
                }
                currentPath.append(part);
                String key = currentPath.toString();

                Node currentNode = nodeMap.getOrDefault(key, new Node(key));
                nodeMap.putIfAbsent(key, currentNode);

                if (parent != null) {
                    if (!parent.children.contains(currentNode)) {
                        parent.children.add(currentNode);
                    }
                } else {
                    root = currentNode;
                }

                parent = currentNode;
            }
        }

        return root;
    }

    private static void generatePaths(Node node, List<String> path, List<String> result) {
        if (node == null) return;

        path.add(node.value);

        if (node.children.isEmpty()) {
            result.add(String.join("\\", path));
        } else {
            for (Node child : node.children) {
                generatePaths(child, new ArrayList<>(path), result);
            }
        }
    }
}