求两个节点的最近公共祖先节点

import java.util.Scanner;/** * 1330 Nearest Common Ancestors * Time Limit: 1000MSMemory Limit: 10000K * Total Submissions: 4632Accepted: 2438 * @author zhtsuc * */public class NearestCommonAnestor {private int[] arr;public void solve(){Scanner in = new Scanner(System.in);int caseNum = in.nextInt();while(caseNum != 0){int nodeNum = in.nextInt();arr = new int[nodeNum + 1];for(int i = 1; i <= nodeNum - 1; i++){int parentNode = in.nextInt();int childNode = in.nextInt();arr[childNode] = parentNode;}int firstNode = in.nextInt();int secondNode = in.nextInt();int nearestCommonAnestor = getNearestCommonAnestor(firstNode, secondNode); System.out.println(nearestCommonAnestor);caseNum--;}}private int getNearestCommonAnestor(int firstNode, int secondNode){while(firstNode != 0){if (isParent(secondNode, firstNode)){return firstNode;}firstNode = arr[firstNode];}return -1;}private boolean isParent(int srcNode, int parentNode){int node = srcNode;while(node != 0){if (node == parentNode){return true;}node = arr[node];}return false;}public static void main(String[] args) {NearestCommonAnestor tree = new NearestCommonAnestor();tree.solve();}}