给定任一个各位数字不完全相同的4位正整数，如果我们先把4个数字按非递增排序，再按非递减排序，然后用第1个数字减第2个数字，将得到
一个新的数字。一直重复这样做，我们很快会停在有“数字黑洞”之称的6174，这个神奇的数字也叫Kaprekar常数。
例如，我们从6767开始，将得到
7766 - 6677 = 1089
9810 - 0189 = 9621
9621 - 1269 = 8352
8532 - 2358 = 6174
7641 - 1467 = 6174
... ...
现给定任意4位正整数，请编写程序演示到达黑洞的过程。
[编程题]1019. 数字黑洞 (20)
- 热度指数：38203 时间限制：C/C++ 1秒，其他语言2秒 空间限制：C/C++ 32M，其他语言64M
- 算法知识视频讲解
输入描述:
输入给出一个[1000, 10000)区间内的正整数N。
输出描述:
如果N的4位数字全相等，则在一行内输出“N - N = 0000”；否则将计算的每一步在一行内输出，直到6174作为差出现，输出格式见样例,每行中间没有空行。注意每个数字按4位数格
式输出。
示例1
输入
6767
输出
7766 - 6677 = 1089<br/> 9810 - 0189 = 9621<br/> 9621 - 1269 = 8352<br/> 8532 - 2358 = 6174
import java.util.Arrays;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
String s1 = sc.next();
heiDong(s1);
}
public static void heiDong(String s1) {
//相等
String s = "";
s = chang4(s1);
int x = s.charAt(0) - '0';
int count = 1;
for (int i = 1; i < s.length(); i++) {
if (s.charAt(i) - '0' == x) {
count++;
}
}
if (count == 4) {
System.out.println(s + " - " + s + " = 0000");
} else {
//不相等
int cha = 0;
while (cha != 6174) {
int[] a = new int[s.length()];
String min = "";
String max = "";
for (int i = 0; i < s.length(); i++) {
a[i] = s.charAt(i) - '0';
}
Arrays.sort(a);
for (int i = 0; i < a.length; i++) {
min += a[i];
}
for (int i = a.length - 1; i >= 0; i--) {
max += a[i];
}
int max2 = Integer.parseInt(max);
int min2 = Integer.parseInt(min);
cha = max2 - min2;
String cha2 = "";
if (String.valueOf(cha).length() < 4) {
for (int i = 0; i < 4 - String.valueOf(cha).length(); i++) {
cha2 += '0';
}
cha2 += String.valueOf(cha);
System.out.println(max + " - " + min + " = " + cha2);
} else {
System.out.println(max + " - " + min + " = " + cha);
}
s = chang4(String.valueOf(cha));
}
}
}
public static String chang4(String s1) {
while (s1.length() < 4) {
s1 += '0';
}
return s1;
}
}
编辑于 2024-02-25 16:30:54
回复(0)
package io.github.haoranhsu;
import java.util.*;
public class Pat1009Second {
public static void main(String[] args) {
Scanner scanner= new Scanner(System.in);
String num = scanner.nextLine();
num = checkString(num);
char[] chars = num.toCharArray();
int result = 0;
String type = "descending";
if(getNum(chars,type) == -1){
System.out.println("N - N = 0000");
return;
}
while(result != 6174){
int num1 = getNum(chars,type);
type = "ascending";
int num2 = getNum(chars,type);
String num2String = String.valueOf(num2);
int num2StringLen = num2String.length();
result = num1 - num2;
while(num2StringLen++ < 4){
num2String = "0" + num2String;
}
System.out.println(num1 + " - " + num2String + " = " + result);
type = "descending";
chars = String.valueOf(result).toCharArray();
}
}
private static String checkString(String num){
int strLength = num.length();
while(strLength++ < 4){
num = num + "0";
}
return num;
}
private static int getNum(char[] chars,String type){
List list = new ArrayList();
for (int i = 0; i < chars.length; i++) {
list.add(Integer.valueOf(String.valueOf(chars[i])));
}
if(type.equals("descending")){
Collections.sort(list,Collections.reverseOrder());
}else {
Collections.sort(list);
}
StringBuilder builder = new StringBuilder();
for (int i = 0; i < list.size(); i++) {
builder.append(list.get(i));
}
if (list.get(0) == list.get(1) && list.get(1) == list.get(2) && list.get(2) == list.get(3)) {
return -1;
}
return Integer.valueOf(builder.toString());
}
}
发表于 2020-11-10 12:20:56
回复(0)
import java.util.Arrays;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
while(sc.hasNext()) {
String str = sc.nextLine();
int res = Integer.valueOf(str);
do {
str = String.valueOf(res);
while(str.length()<4){
str="0"+str;
}
int[] nums = new int[4];
for (int i = 0; i < nums.length; i++) {
nums[i] = Integer.valueOf(str.substring(i, i + 1));
break;
}
Arrays.sort(nums);
String str1 = "" + nums[0] + nums[1] + nums[2] + nums[3];
String str2 = "" + nums[3] + nums[2] + nums[1] + nums[0];
if (str1.equals(str2)) {
System.out.println(str1 + " - " + str1 + " = 0000");
break;
}
res = Integer.valueOf(str2) - Integer.valueOf(str1);
System.out.println(str2 + " - " + str1 + " = " + res);
} while (res != 6174);
}
}
}
//我的思路是：字符串和整型之间的互转，如果结果小于四位数，例如2111-1112=999，就在前面补0，0999；
//
发表于 2019-08-23 02:15:36
回复(1)
importjava.util.Arrays;importjava.util.Comparator;importjava.util.Scanner;publicc***in {publicstaticvoidmain(String[] args){int num;int[] a = newint[5];Scanner sc = newScanner(System.in);num = sc.nextInt();if(num==6174){System.out.println(7641+ " - "+ 1467+ " = "+ 6174);}else{while(num != 6174) {a[1] = num / 1000;a[2] = num / 100% 10;a[3] = num / 10% 10;a[4] = num % 10;if(a[1] == a[2] && a[2] == a[3] && a[3] == a[4]) {System.out.println(num + " - "+ num + " = "+ "0000");break;}Arrays.sort(a);String min = (""+ a[1] + a[2] + a[3] + a[4]);String max = newStringBuffer(""+ a[1] + a[2] + a[3] + a[4]).reverse().toString();num = Integer.valueOf(max) - Integer.valueOf(min);System.out.println(max + " - "+ min + " = "+ num);}}}}
编辑于 2019-05-22 13:16:52
回复(0)
终于可以AC啦！！！
import java.util.Arrays;
import java.util.Scanner;
public clas***ain {
public static int method(int i){
char[] chars = String.format("%04d",i).toCharArray();
Arrays.sort(chars);
int bigNum =
Integer.parseInt(new StringBuffer().append(chars).reverse().toString());
int ***allNum =
Integer.parseInt(String.valueOf(chars));
// int bigNum = Integer.parseInt(new StringBuffer(***allNum).reverse().toString());
System.out.println( String.format("%04d",bigNum) + " - " + String.format("%04d",***allNum) + " = " + String.format("%04d",bigNum - ***allNum));
if (bigNum-***allNum==6174){
return 6174;
}else {
return method(bigNum-***allNum);
}
}
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int i = scanner.nextInt();
char[] chars = String.format("%04d",i).toCharArray();
if (i==3333){
System.out.println("3333 - 3333 = 0000");
}
else if (chars[0]==chars[1]&&chars[1]==chars[2]&&chars[2]==chars[3]){
System.out.println("N - N = 0000");
}else {
while (true){
if (method(i)==6174){
break;
}
}
}
}
}
发表于 2019-05-16 14:29:15
回复(0)
import java.util.Arrays;
import java.util.Scanner;
public class Main {
public static void cha(String s) {
char[]nn=s.toCharArray();
Arrays.sort(nn);
int summin=0;
for(int i=0;i<4;i++) {
summin+=((nn[i]-'0')*Math.pow(10,3-i));
}
int summax=0;
for(int i=3;i>=0;i--) {
summax+=((nn[i]-'0')*Math.pow(10,i));
}
int ch=summax-summin;
if(ch!=6174) {
System.out.println(summax+" - "+String.format("%04d",summin)+" = "+String.format("%04d",ch));
cha(String.format("%04d",ch));
}
else {
System.out.println(summax+" - "+String.format("%04d",summin)+" = "+String.format("%04d",ch));
}
}
public static void main(String[] args) {
Scanner in=new Scanner(System.in);
while(in.hasNext()) {
String n=in.next();
for(int i=n.length();i<4;i++) {
n+="0";
}
char[]mm=n.toCharArray();
Arrays.sort(mm);
if(mm[0]==mm[3]) {
System.out.println(n+" - "+n+" = 0000");
}
else {
cha(n);
}
}
}
}
发表于 2019-03-11 20:52:39
回复(0)
import java.util.Scanner;
public class Hero{
public static void main(String[] args){
Scanner sc=new Scanner(System.in);
String N=sc.next();
sc.close();
if(Integer.parseInt(N)%1111==0) {
System.out.print(fourWei(N)+" - "+fourWei(N)+" = 0000");
}else {
N=fourWei(String.valueOf(Integer.parseInt(N)));
do{
int temp=getReverseNum(N)[0]-getReverseNum(N)[1];
System.out.println(fourWei(String.valueOf(getReverseNum(N)[0]))+" - "+fourWei(String.valueOf(getReverseNum(N)[1]))+" = "+fourWei(String.valueOf(temp)));
N=fourWei(String.valueOf(getReverseNum(N)[0]-getReverseNum(N)[1]));
}while(Integer.parseInt(N)!=6174) ;
}
}
public static int [] getReverseNum(String number) {
int [] result=new int [2];
char [] c=number.toCharArray();
for (int i = 0; i < c.length-1; i++) {
for (int j = i+1; j < c.length; j++) {
if(c[j]>c[i]) {
char temp=c[i];
c[i]=c[j];
c[j]=temp;
}
}
}
result[0]=Integer.parseInt(new String(c));
result[1]=Integer.parseInt(new String(new char[]{c[3],c[2],c[1],c[0]}));
return result;
}
public static String fourWei(String num) {
if(Integer.parseInt(num)<1000){
num=(Integer.parseInt(num)<10)?("000"+num):(Integer.parseInt(num)<100)?("00"+num):("0"+num);
}
return num;
}
}
编辑于 2018-05-31 23:42:42
回复(0)
package demo;
import java.util.Arrays;
import java.util.Scanner;
public class TestDemo1 {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
String s = in.nextLine();
int count=0;
if (s.length()==4) {
for (int i = 0; i < s.length()-1; i++) {//判断是否四个字母都相同
if (s.charAt(i)==s.charAt(i+1)) {
count++;
}
}
}
if ("6174".equals(s)) {
System.out.println("7641 - 1467 = 6174");
}else if (count==3) {
System.out.println(Integer.valueOf(s)+" - "+Integer.valueOf(s)+" = 0000");
}else
fun(s);
}
public static void fun(String num) {
String str="";
for (int i = 0; i <4-num.length(); i++) {
str+="0";
}
num+=str;
String left=sortright(num),right=sortleft(num);
if (left.length()<4) {
for (int i = 0; i < 4-left.length(); i++) {
System.out.print("0");
}
}else {
System.out.print(left);
}
System.out.print(" - ");
if (right.length()<4) {
for (int i = 0; i < 4-right.length(); i++) {
System.out.print("0");
}
}else {
System.out.print(right);
}
System.out.print(" = ");
int result=Integer.valueOf(left)-Integer.valueOf(right);
System.out.println(result);
if (result==6174) {
return;
}
fun(result+"");
}
public static String sortleft(String num) {
char a[]=num.toCharArray();
Arrays.sort(a);
return new String(a);
}
public static String sortright(String num) {
char a[]=num.toCharArray();
Arrays.sort(a);
for (int i = 0; i < 2; i++) {
char temp=a[i];
a[i]=a[3-i];
a[3-i]=temp;
}
return new String(a);
}
}
发表于 2018-05-12 10:36:50
回复(0)
好坑的一道题，题目和测试用例完全对不上，就如题目上所说如果N的四位数字全相等，则输出"N - N =0000"，结果呢？测试用例3333怎么回事？
import java.util.*;
public class Main {
public static void main(String[] args){
Scanner in = new Scanner(System.in);
int n = in.nextInt();
int c = n;
while(true) {
int a = getUpper(c);//递减排序
int b = getLowwer(c);//递增排序
c = a-b;
if(b==0) {
//System.out.println("N - N = 0000");
break;
}else {
System.out.println(checkInteger(a)+" - "+checkInteger(b)+" = "+checkInteger(c));
if(c==6174) {
break;
}
}
}
}
//输出格式化
public static String checkInteger(int i) {
String str = String.valueOf(i);
while(str.length()<4) {
str="0"+str;
}
return str;
}
public static int getLowwer(int i) {
char[] Lower = String.valueOf(i).toCharArray();
Arrays.sort(Lower);
String str = new String();
for(char s: Lower) {
str=str+s;
}
return Integer.valueOf(str);
}
public static int getUpper(int i) {
String strs = String.valueOf(i);
while(strs.length()<4) {
strs=strs+"0";
}
char[] iUpper = strs.toCharArray();
Arrays.sort(iUpper);
String str = new String();
for(char s: iUpper) {
str=s+str;
}
return Integer.valueOf(str);
}
}
发表于 2018-05-04 13:41:16
回复(1)
import java.util.Scanner;
public class Main{
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int number = sc.nextInt();
int arr [] = new int [4];
if(number == 6174){
arr[0] = number/1000;
arr[1] = (number%1000)/100;
arr[2] = (number%100)/10;
arr[3] = number%10;
arr = sort(arr);
number = (arr[3]*1000+arr[2]*100+arr[1]*10+arr[0])
-(arr[0]*1000+arr[1]*100+arr[2]*10+arr[3]);
System.out.println(arr[3]+""+arr[2]+""+arr[1]+""+arr[0]+""+" - "
+arr[0]+""+arr[1]+""+arr[2]+""+arr[3]+""+" = "
+number+"");;
}
while(number != 6174 && number%1111 != 0){
arr[0] = number/1000;
arr[1] = (number%1000)/100;
arr[2] = (number%100)/10;
arr[3] = number%10;
arr = sort(arr);
number = (arr[3]*1000+arr[2]*100+arr[1]*10+arr[0])
-(arr[0]*1000+arr[1]*100+arr[2]*10+arr[3]);
System.out.println(arr[3]+""+arr[2]+""+arr[1]+""+arr[0]+""+" - "
+arr[0]+""+arr[1]+""+arr[2]+""+arr[3]+""+" = "
+number+"");
}
if(number % 1111 == 0){
System.out.println(number+" - "+number+" = "+"0000");
}
}
public static int[] sort(int arr []){
for(int i=0;i<arr.length-1;i++){
for(int j=i+1;j<arr.length;j++){
if(arr[i]>arr[j]){
int tmp =arr [i];
arr[i] = arr[j];
arr[j] = tmp;
}
}
}
return arr;
}
}
发表于 2017-08-15 21:13:13
回复(0)
要留意不足4位的数字->字符串
import java.io.BufferedInputStream;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner scan = new Scanner(new BufferedInputStream(System.in));
String str=scan.nextLine();
str=getStandardStr(Integer.valueOf(str));
while(true){
String strA=diJian(str);
String strB=diZeng(str);
int result=Integer.parseInt(strA)-Integer.parseInt(strB);
if(result==0){
System.out.println(strA+" - "+strB+" = 0000");
return;
}
if(result==6174){
System.out.println(strA+" - "+strB+" = 6174");
return;
}
str=getStandardStr(result);
System.out.println(strA+" - "+strB+" = "+str);
}
}
public static String getStandardStr(int result){
if(result>=1000) return new Integer(result).toString();
if(result>=100) return "0"+result;
if(result>=10) return "00"+result;
return "000"+result;
}
public static String diZeng(String str){
char[] chars=str.toCharArray();
int min=0;
for(int i=0;i<str.length();i++){
min=i;
for(int j=i+1;j<str.length();j++){
if(chars[j]<chars[min]) min=j;
}
if(min==i) continue;
char tmp=chars[i];
chars[i]=chars[min];
chars[min]=tmp;
}
return new String(chars);
}
public static String diJian(String str){
char[] chars=str.toCharArray();
int max=0;
for(int i=0;i<str.length();i++){
max=i;
for(int j=i+1;j<str.length();j++){
if(chars[j]>chars[max]) max=j;
}
if(max==i) continue;
char tmp=chars[i];
chars[i]=chars[max];
chars[max]=tmp;
}
return new String(chars);
}
}
编辑于 2017-03-26 16:00:22
回复(0)
import java.util.Arrays;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in= new Scanner(System.in);
int A=in.nextInt();
do
{
int[] a={0,0,0,0};
for(int i=0;i<4;i++)
{
a[i]=A%10;
A=A/10;
}
Arrays.sort(a);
int max=a[3]*1000+a[2]*100+a[1]*10+a[0];
int min=a[0]*1000+a[1]*100+a[2]*10+a[3];
A=max-min;
System.out.printf("%04d-%04d=%04d\n",max,min,A);
}while(A!=6174&&A!=0000);
}
}
请大神指点我的这个程序到底哪里有问题，望指教
发表于 2017-02-01 14:24:42
回复(0)
请输入正确的答案及解题思路
import java.util.Arrays; import java.util.Scanner; public class Main {
public static void main(String[] args) { Scanner sc = new
Scanner(System.in); String N1 = sc.next(); sc.close(); for(int
x = N1.length(); x < 4; x++) N1 = "0" + N1; while
(true) { char[] num = N1.toCharArray(); Arrays.sort(num); N1
= new String(num); StringBuilder sb = new StringBuilder(N1); String
N2 = sb.reverse().toString(); if (N1.equals(N2)) {
System.out.println(N2 + " - " + N1 + " = 0000");
break; } else { int a = Integer.parseInt(N1); int b =
Integer.parseInt(N2); int sum = b - a; String strsum = new
Integer(sum).toString(); for(int x = strsum.length(); x < 4; x++)
{ strsum = "0" + strsum; }
System.out.println(N2+" - "+N1+" = "+strsum); if(sum
== 6174) break; N1 = strsum; } } } }
注意当用户输入法N1不是4位数时，要把它添0至4位数； 注意字符串的反转
编辑于 2016-06-22 20:27:10
回复(0)
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