hihocoder 1069最近公共祖先(DFS + ST)java实现

package tree;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.Map.Entry;

import java.util.Scanner;

/*

 * 8

adam sam

sam joey

tom lv

tom lee

kevin john

adam kevin

sam peter

sam tom

 */

public class Week17 {

public static void main(String[] args) {

Scanner scanner =new Scanner(System.in);

int datanum = Integer.parseInt(scanner.nextLine());

HashMap<String, ArrayList<String>> DFSmap = new HashMap<String, ArrayList<String>>();

ArrayList<DFSNode17> DFSarrAdep = new ArrayList<DFSNode17>();

HashMap<String, Integer> fAppearMap = new HashMap<String, Integer>();

DFSNode17 [][]ST =new DFSNode17[2*datanum + 2][2*datanum + 2];

String admisssion =null;

for(inti=0;i<datanum;i++){

String data =scanner.nextLine();

String father =data.split(" ")[0];

String son =data.split(" ")[1];

if(i==0)admisssion =father;

Week17.createDFSmap(DFSmap,father,son);

}

Week17.DFS(admisssion, 0,DFSmap,DFSarrAdep,fAppearMap);

Week17.createST(DFSarrAdep,ST);

int querynum = Integer.parseInt(scanner.nextLine());

for(inti=0;i<querynum;i++){

String data =scanner.nextLine();

String p1 =data.split(" ")[0];

String p2 =data.split(" ")[1];

Week17.searchST(p1,p2,ST, fAppearMap);

}

}

public static void createDFSmap(HashMap<String, ArrayList<String>>DFSmap, Stringfather, Stringson){

if(DFSmap.containsKey(father)){

ArrayList<String> temp = DFSmap.get(father);

temp.add(son);

}

else{

ArrayList<String> temp = new ArrayList<String>();

temp.add(son);

DFSmap.put(father,temp);

}

}

public static void DFS(String admisssion, int depth, HashMap<String, ArrayList<String>> DFSmap, ArrayList<DFSNode17>DFSarrAdep, HashMap<String, Integer>fAppearMap){

DFSarrAdep.add(new DFSNode17(admisssion,depth));

if(!fAppearMap.containsKey(admisssion))fAppearMap.put(admisssion,DFSarrAdep.size()-1);

if(DFSmap.containsKey(admisssion)){

ArrayList<String> temp = DFSmap.get(admisssion);

for(inti=0;i<temp.size();i++){

DFS(temp.get(i), ++depth,DFSmap,DFSarrAdep,fAppearMap);

depth--;

DFSarrAdep.add(new DFSNode17(admisssion,depth));

}

}

}

public static void createST(ArrayList<DFSNode17>DFSarrAdep, DFSNode17 [][]ST){

for(inti=1;i<ST[0].length;i*=2){

for(intj=1;j<ST.length;j++){

if(i==1)ST[j][i] =DFSarrAdep.get(j-1);

else{

if(j +i/2 <ST.length){

int depth1 = ST[j][i/2].getDepth();

int depth2 = ST[j +i/2][i/2].getDepth();

ST[j][i] =depth1 >depth2 ?ST[j +i/2][i/2] :ST[j][i/2];

}

else ST[j][i] =ST[j][i/2];

}

}

}

}

public static void searchST(String p1, String p2, DFSNode17 [][]ST, HashMap<String, Integer>fAppearMap){

if(p1.equals(p2)) System.out.println(p1);

else{

intappear1 =fAppearMap.get(p1) + 1;

intappear2 =fAppearMap.get(p2) + 1;

intleft,right;

if(appear1 >appear2){

left =appear2;

right =appear1;

}

else{

left =appear1;

right =appear2;

}

int range = right - left + 1;

int power = 0;

while(range != 0){

range >>= 1;

power++;

}

int depth1 = ST[left][(int)Math.pow(2,power-1)].getDepth();

int depth2 = ST[right - (int)Math.pow(2,power-1) + 1][(int)Math.pow(2,power-1)].getDepth();

String name =depth1 <=depth2 ?ST[left][(int)Math.pow(2,power-1)].getValue() : 

ST[right - (int)Math.pow(2,power-1) + 1][(int)Math.pow(2,power-1)].getValue(); 

System.out.println(name);

}

}

}

class DFSNode17{

private Stringvalue;

privateintdepth;

public DFSNode17(Stringvalue,int depth){

this.value =value;

this.depth =depth;

}

public String getValue() {

returnvalue;

}

public void setValue(String value) {

this.value =value;

}

public int getDepth() {

returndepth;

}

public void setDepth(int depth) {

this.depth =depth;

}

}