三道Java算法面试题

下面是某些企业常见的算法面试试题，现总结如下，仅供学员参考与学习。

1.比较两个字符串如果不等返回True？
答案： 
 

 package com.test.kaoshi;

 public class StringDemo {

     private static String a = "abc";
     private static String b = "abcg";

     public static boolean equalString() {
         if (a.equals(b)) {
             return false;
         } else {

             return true;
         }
     }
     public static void main(String[] args) {
         StringDemo  sd = new StringDemo();
         System.out.println("主要考察返回Boolean变量和字符串比较使用的方法?+sd.equalString());
     }
 }

 package com.test.kaoshi;

 public class StringDemo {

     private static String a = "abc";
     private static String b = "abcg";

     public static boolean equalString() {
         if (a.equals(b)) {
             return false;
         } else {

             return true;
         }
     }
     public static void main(String[] args) {
         StringDemo  sd = new StringDemo();
         System.out.println("主要考察返回Boolean变量和字符串比较使用的方法?+sd.equalString());
     }
 }

2.随机产生20个字符并且排序？ 

答案： 
 

 package com.test.kaoshi;

 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.Random;
 import java.util.Set;
 import java.util.TreeSet;

 public class RadomDemo {
 /**
  * 随机产生20个字符串并且字符串不能重复 且进行排序
  * @param random
  * @param len
  * @return
  */
     public Set getChar(){

         Set numberSet01 = new HashSet();
         Random rdm = new Random();
         char ch;
         while(numberSet01.size()<20){
            int rdGet = Math.abs(rdm.nextInt())%26+97;//产生97到122的随机数a-z值
             ch=(char)rdGet;
             numberSet01.add(ch);
             //Set中是不能放进重复的值的，当它有20个时，就满足你的条件了
         }
           return numberSet01;
         }
     public static void main(String[] args) {
         RadomDemo rd = new RadomDemo();
         Set numberSet01=rd.getChar();

         Set numberSet = new TreeSet();
         numberSet.addAll(numberSet01);
         for(Iterator it=numberSet01.iterator();it.hasNext();){
             System.out.print(it.next());
             }
         System.out.println();
         for(Iterator it=numberSet.iterator();it.hasNext();){
             System.out.print(it.next());
             }
     }
 }

 package com.test.kaoshi;

 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.Random;
 import java.util.Set;
 import java.util.TreeSet;

 public class RadomDemo {
 /**
  * 随机产生20个字符串并且字符串不能重复 且进行排序
  * @param random
  * @param len
  * @return
  */
     public Set getChar(){

         Set numberSet01 = new HashSet();
         Random rdm = new Random();
         char ch;
         while(numberSet01.size()<20){
            int rdGet = Math.abs(rdm.nextInt())%26+97;//产生97到122的随机数a-z值
             ch=(char)rdGet;
             numberSet01.add(ch);
             //Set中是不能放进重复的值的，当它有20个时，就满足你的条件了
         }
           return numberSet01;
         }
     public static void main(String[] args) {
         RadomDemo rd = new RadomDemo();
         Set numberSet01=rd.getChar();

         Set numberSet = new TreeSet();
         numberSet.addAll(numberSet01);
         for(Iterator it=numberSet01.iterator();it.hasNext();){
             System.out.print(it.next());
             }
         System.out.println();
         for(Iterator it=numberSet.iterator();it.hasNext();){
             System.out.print(it.next());
             }
     }
 }

3.50个人围成一圈数到三和三的倍数时出圈，问剩下的人是谁？在原来的位置是多少？ 


答案： 

 

 package com.test.kaoshi;

 import java.util.Iterator;
 import java.util.LinkedList;

 public class YouXi {
     public static int removeNM(int n, int m) {
         LinkedList ll = new LinkedList();
         for (int i = 0; i < n; i++)
             ll.add(new Integer(i + 1));
         int removed = -1;
         while (ll.size() > 1) {
             removed = (removed + m) % ll.size();
             ll.remove(removed--);
         }
         return ((Integer) ll.get(0)).intValue();
     }

     public static void main(String[] args) {
         System.out.println(removeNM(50, 3));
     }
 }