算法训练 字串统计

 1 import java.text.DecimalFormat;
 2 import java.text.NumberFormat;
 3 import java.util.ArrayList;
 4 import java.util.Arrays;
 5 import java.util.Collection;
 6 import java.util.Collections;
 7 import java.util.List;
 8 import java.util.Scanner;
 9 import java.util.Stack;  
10     public class Main{   
11         public static void main(String[] args){ 
12             Scanner input = new Scanner(System.in);
13             int n = input.nextInt();
14             String s = input.next();
15             List<A> list = new ArrayList<A>();
16             int h = 0;
17             String temp;
18             for(int i=0;i<s.length();i++){
19                 for(int j=i+1;j<=s.length();j++){
20                     if(j-i>=n){
21                         temp = s.substring(i, j);
22                         int k;
23                         for(k=0;k<list.size();k++){
24                             if(temp.equals(list.get(k).s)){
25                                 list.get(k).n++;
26                                 break;
27                             }
28                             
29                         }
30                         if(k==h){
31                             A a = new A();
32                             a.s = temp;
33                             a.time = h;
34                             list.add(a);
35                             h++;
36                         }
37                     }
38                 }
39             }
40             Collections.sort(list);
41             System.out.println(list.get(list.size()-1).s);
42         }
43         static class A implements Comparable<A>{
44             String s;
45             int n;
46             int time;
47             @Override
48             public int compareTo(A a) {
49                 // TODO Auto-generated method stub
50                 int result;
51                 if(n!=a.n){
52                     result = n-a.n;
53                 }else if(s.length()!=a.s.length()){
54                     result = s.length()-a.s.length();
55                 }else{
56                     result = a.time-time;
57                 }
58                 return result;
59             }
60         }
61  }