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java面试题 20170908
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第一题 使用 list ?map 效果，会比我自己写的算法，快很多倍，所以算法应该是类似list map 的更快
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class="java">package com.baoy.cn.study201707.test;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class Mainshi1 {
public static void main(String[] args) {
String[] a = { "a", "b", "a","c", "a", "aaa", "aaa" ,"a","b","c"};
long start1 = System.currentTimeMillis();
String[] b = compare(a);
String resultbString = Arrays.toString(b);
System.out.println(resultbString.substring(1, resultbString.length()-1).replace(" ",""));
long end1 = System.currentTimeMillis();
long start2 = System.currentTimeMillis();
List<String> compare2 = compare2(a);
String[] resultarr = (String[]) compare2.toArray(new String[compare2.size()]);
String resultString = Arrays.toString(resultarr);
System.out.println(resultString.substring(1, resultString.length()-1).replace(" ",""));
long end2= System.currentTimeMillis();
System.out.println((end1-start1)+"\r\n"+(end2-start2));
}
public static boolean compareLength(String[] param, int index, int current) {
if (param[index].length() == param[current].length()) {
return true;
}
return false;
}
public static boolean compareContent(String[] param, int index, int current) {
if (compareLength(param, index, current)) {
char[] indexChar = param[index].toCharArray();
int i = 0;
while (i < indexChar.length) {
if (param[current].charAt(i) != indexChar[i]) {
return false;
}
i++;
}
return true;
} else {
return false;
}
}
public static String[] compare(String[] param) {
boolean[] flag = new boolean[param.length];
for (int i = 0; i < flag.length; i++) {
flag[i] = true;
}
String[] temp = new String[param.length];
for (int i = 0; i < param.length; i++) {
if (flag[i]) {
temp[i] = param[i];
int k = 0;
for (int j = i + 1; j < temp.length; j++) {
if (compareContent(param, i, j)) {
k++;
flag[j] = false;
temp[j] = param[j] + (k == 0 ? "" : k);
}
}
}
}
return temp;
}
public static List<String> compare2(String[] param) {
List<String> list = new ArrayList<String>();
Map<String,Integer> map = new HashMap<String, Integer>();
for (int i = 0; i < param.length; i++) {
if (!map.containsKey(param[i])) {
map.put(param[i],0);
list.add(param[i]);
}else{
map.put(param[i], map.get(param[i])+1);
list.add(param[i]+map.get(param[i]));
}
}
return list;
}
}
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package com.baoy.cn.study201707.test;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
public class Mainshi2 {
public static void main(String[] args) throws ParseException {
String[] params = {"20170101 00:02:01", "20170101 05:04:02" ,"20170101 10:06:03", "20170101 15:08:04"};
test(params);
}
public static void test(String []param) throws ParseException{
SimpleDateFormat sdf = new SimpleDateFormat( "yyyyMMdd HH:mm:ss" );
Date date1 = sdf.parse(param[0]);
Date date2 = sdf.parse(param[1]);
long a = date2.getTime() -date1.getTime();
Calendar calendar=Calendar.getInstance();
calendar.setTimeInMillis(a);
int hour =calendar.get(Calendar.HOUR);
int minute =calendar.get(Calendar.MINUTE);
int seconds =calendar.get(Calendar.SECOND);
long day = a / (1000 * 60 * 60 * 24);
long month= a / (1000 * 60 * 60 * 24) /30 ;
long year= a / (1000 * 60 * 60 * 24)/365;
System.out.println(
(year > 0 ? year+"year":"")+
(month > 0 ? month+"month":"")+
(day > 0 ? day+"day":"")+
hour+"hour"+minute+"minute"+seconds+"second"
);
}
}
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package com.baoy.cn.study201707.test;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
public class Mainshi3 {
public static void main(String[] args) {
String[] params = { "A", "B", "C", "D" };
String[] rules = { "A->C", "B->C", "D->C" };
List<String> list = new ArrayList<String>();
order(list, "","", params);
// [ ABCD, ABDC, ACBD, ACDB, ADBC, ADCB,
// BACD, BADC, BCAD, BCDA, BDAC, BDCA,
// CABD, CADB, CBAD, CBDA, CDAB, CDBA,
// DABC, DACB, DBAC, DBCA, DCAB, DCBA]
List<String> ordersort = ordersort(list, rules);
String[] resultarr = (String[]) ordersort.toArray(new String[ordersort.size()]);
String resultString = Arrays.toString(resultarr);
System.out.println(resultString.substring(1, resultString.length()-1).replace(" ",""));
}
public static List<String> ordersort(List<String> res,String[] rules){
List<String> list = new ArrayList<String>();
for (int i = 0; i < res.size(); i++) {
String line = res.get(i);
boolean flag = true;
for (int j = 0; j < rules.length; j++) {
String[] rule = rules[j].split("->");
if (line.indexOf(rule[0]) > line.indexOf(rule[1])) {
flag =false;
}
}
if (flag) {
list.add(line);
}
}
return list;
}
public static void order(List<String> res,String preffix,String temp, String[] a) {
preffix += temp ;
if (a.length > 1) {
for (int i = 0; i < a.length; i++) {
List<String> list = Arrays.asList(a);
List<String> list2 = new ArrayList<String>(Arrays.asList(new String[list.size()]));
Collections.copy(list2, list);
temp = a[i];
list2.remove(i);
String[] b = (String[]) list2.toArray(new String[list2.size()]);
order(res,preffix,temp, b);
}
} else {
res.add(preffix+a[0]);
}
}
}
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package com.baoy.cn.study201707.test;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class Mainshi4 {
public static void main(String[] args) {
int N1 =2;
int N2 =3 ;
print(N1, N2);
}
public static void print(int n1 ,int n2){
if(n1 ==0 && n1 ==1 &&n2 ==0 && n2 ==1){
System.out.println("null");
}
String n1s = getCode(n1);
String n2s = getCode(n2);
List<String> list = new ArrayList<String>();
for (int i = 0; i < n1s.length() ; i++) {
String one= n1s.substring(i, i+1);
for (int j = 0; j < n2s.length(); j++) {
String two= n2s.substring(j, j+1);
list.add(one+two);
}
}
String[] arr = (String[]) list.toArray(new String[list.size()]);
String resultString = Arrays.toString(arr);
System.out.println(resultString.substring(1, resultString.length()-1).replace(" ",""));
}
public static String getCode(int key) {
switch (key) {
case 1:
return "";
case 2:
return "abc";
case 3:
return "def";
case 4:
return "ghi";
case 5:
return "jlk";
case 6:
return "mno";
case 7:
return "pqrs";
case 8:
return "tuv";
case 9:
return "wxyz";
case 0:
return "";
default:
break;
}
return "";
}
}
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package com.baoy.cn.study201707.test;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
public class Mainshi6 {
public static void main(String[] args) {
int[] weight =new int []{ 7, 5, 3, 2, 6, 1, 4, 9};
String[] s =new String []{"A","B","C","D","E","F","G","H"};
sort(weight, s, 5);
}
public static void sort(int[] weight,String[] s,int n){
List <Alphabet> list = new ArrayList<Alphabet>();
int []all = new int [weight.length];
for (int i = 0; i < s.length; i++) {
list.add(new Alphabet(weight[i],s[i]));
}
Collections.sort(list);
for (int i = 0; i < n; i++) {
System.out.print(list.get(i).alphabet);
}
}
}
class Alphabet implements Comparable<Alphabet>{
public int allweight;
public String alphabet;
public Alphabet(){}
public Alphabet(int allweight, String alphabet) {
this.allweight = allweight;
this.alphabet = alphabet;
}
@Override
public int compareTo(Alphabet o) {
if (this.allweight > o.allweight) {
return 1;
}else if (this.allweight == o.allweight) {
return 0;
}
return -1;
}
}
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package com.baoy.cn.study201707.test;
import java.util.ArrayList;
import java.util.List;
public class Mianshi9 {
public static void main(String[] args) {
Node a = new Node("A", null);
Node b = new Node("B", null);
Node c = new Node("C", null);
Node d = new Node("D", null);
Node e = new Node("E", null);
Node f = new Node("F", null);
Node g = new Node("G", null);
Node h = new Node("H", null);
Node i = new Node("I", null);
c.setChild(f);
c.setChild(g);
c.setChild(h);
b.setChild(e);
d.setChild(i);
a.setChild(b);
a.setChild(c);
a.setChild(d);
a.test(a, c);
}
}
class Node{
public String data;
public List<Node> list;
public Node(){}
public Node(String data, List<Node> list) {
this.data = data;
this.list = list;
}
public void setChild(Node node){
if (list == null ) {
list = new ArrayList<Node>();
}
list.add(node);
}
public void order(Node localroot,Node red){
if(localroot.list != null){
for (Node node : localroot.list) {
if (!node.data.equals(red.data)) {
System.out.print(node.data);
}
}
for (Node node : localroot.list) {
if (!node.data.equals(red.data)) {
order(node, red);
}
}
}
}
public void test(Node root ,Node red){
System.out.print(root.data);
root.order(root, red);
}
}
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