JAVA考试问题及答案整数的分划问题

整数的分划问题。
如，对于正整数n=6，可以分划为：
6
5+1
4+2, 4+1+1
3+3, 3+2+1, 3+1+1+1
2+2+2, 2+2+1+1, 2+1+1+1+1
1+1+1+1+1+1+1
现在的问题是，对于给定的正整数n,编写算法打印所有划分。
用户从键盘输入 n （范围1~10）
程序输出该整数的所有划分。
 
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;
 
public class MyTest {
       public static void main(String[] args) {
              Scanner in = new Scanner(System.in);
              int x = in.nextInt();
              List expressions[] = new List[x];
              for(int i=1;i<=x;i++){
                     if(i==1){
                            expressions[i-1] = new ArrayList();
                            expressions[i-1].add("1");
                     }else{
                            expressions[i-1] = new ArrayList();
                            expressions[i-1].add(String.valueOf(i));
                            //expressions[i-1].add(String.valueOf(i-1)+"+1");
                            for(int j=i-1;j>=i/2;j--){
                                   for(int k=0;k<expressions[j-1].size();k++){
                                          // 原来的表达式
                                          String str1=(String)expressions[j-1].get(k);
                                          // 排序后的表达式
                                          String str2=process(str1+"+"+(i-j));
                                          // 查找是否已经存在
                                          boolean b=false;
                                          for(int kk=0;kk<expressions[i-1].size();kk++){
                                                 if(expressions[i-1].get(kk).toString().equals(str2)){
                                                        b = true;
                                                        break;
                                                 }
                                          }
                                          if(!b){
                                                 expressions[i-1].add(str2);
                                          }
                                   }
                            }
                     }
              }
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                     Collections.sort(expressions[x-1]);
                     String temp=null;
                     for(int i=expressions[x-1].size()-1;i>=0;i--){
                            String value = expressions[x-1].get(i).toString();
                            if(temp==null){
                                   System.out.print(value);
                                   temp = value.substring(0,1);
                            }else{
                                   if(value.startsWith(temp)){
                                          System.out.print(",");
                                   }else{
                                          System.out.println();
                                          temp = value.substring(0,1);
                                   }
                                   System.out.print(value);
                            }
                     }
            
       }
       /*
        * 调整顺序，例如 3+1+2+1 调整后 3+2+1+1
        */
       static String process(String exp){
              exp = exp.replace("+"," ");
              String str[] = exp.split(" ");
              Arrays.sort(str);
              StringBuffer sb = new StringBuffer();
              for(int i=str.length-1;i>=0;i--){
                     sb.append(str[i]+"+");
              }
              sb.deleteCharAt(sb.length()-1);
              return sb.toString();
       }
     
}

JAVA考试问题及答案整数的分划问题

原文：http://www.cnblogs.com/geziwu/p/3564471.html