PDD第二题代码，供参考。 import java.util.Scanner; public class Main { static class TreeNode { int father; int me; TreeNode firstChild; TreeNode nextSibling; String str; public TreeNode(String str2) { str = str2; firstChild = null; nextSibling = null; } } public static void main(String[] args) { Scanner in = new Scanner(System.in); int N = in.nextInt(); in.nextLine(); TreeNode[] nodes = new TreeNode[N]; for (int i = 0; i < N; i++) { String[] str = in.nextLine().split(" "); nodes[i] = new TreeNode(str[0]); nodes[i].father = Integer.valueOf(str[1]); nodes[i].me = i; } sort(nodes); TreeNode tn = nodes[0]; for (int i = 1; i < N; i++) { TreeNode t = nodes[i]; TreeNode fa = getFather(tn, t.father); TreeNode child = fa.firstChild; if (child != null) { while (child.nextSibling != null) child = child.nextSibling; child.nextSibling = t; } else fa.firstChild = t; } printValues(tn, tn.me, 0); in.close(); } public static void printValues(TreeNode root, int cen, int lie) { if (root == null) return; String temp = ""; String temp2 = ""; if (cen != 0) { for (int i = 0; i < cen - 1; i++) { if (i == 0) { temp += " "; temp2 += " "; continue; } temp += "| "; temp2 += "| "; } temp += "|-- "; temp2 += "`-- "; } if (root.nextSibling != null || lie == 0) System.out.println(temp + root.str); else System.out.println(temp2 + root.str); printValues(root.firstChild, cen + 1, 0); if (root.firstChild != null) printValues(root.firstChild.nextSibling, cen + 1, lie + 1); } public static TreeNode getFather(TreeNode root, int n) { if (root == null || root.me == n) return root; TreeNode tn = getFather(root.firstChild, n); if (tn == null) tn = getFather(root.nextSibling, n); return tn; } public static void sort(TreeNode[] nodes) { for (int i = 0; i < nodes.length; i++) { for (int j = i + 1; j < nodes.length; j++) { if (nodes[i].father > nodes[j].father) { TreeNode t = nodes[i]; nodes[i] = nodes[j]; nodes[j] = t; } else if (nodes[i].father == nodes[j].father) { if (nodes[i].str.compareTo(nodes[j].str) > 0) { TreeNode t = nodes[i]; nodes[i] = nodes[j]; nodes[j] = t; } } } } } } 输出如下： 10 my-app -1 src 0 main 1 java 2 resource 2 webapp 2 test 1 java 6 resource 6 pom.xml 0 my-app |-- pom.xml `-- src |-- main | |-- java | |-- resource `-- test | |-- java | `-- resource