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  1. import java.util.*;
  2.  
  3. class Ideone {
  4.     public static void main(String[] args) {
  5.         final Scanner scanner = new Scanner(System.in);
  6.         int start = scanner.nextInt();
  7.         int end = scanner.nextInt();
  8.  
  9.         final LinkedList<Range> left = leftBounds(start, end);
  10.         final Range lastLeft = left.removeLast();
  11.  
  12.         final LinkedList<Range> right = rightBounds(lastLeft.getStart(), end);
  13.         final Range firstRight = right.removeFirst();
  14.  
  15.         LinkedList<Range> merged = new LinkedList<>();
  16.         merged.addAll(left);
  17.         if (!lastLeft.overlaps(firstRight)) {
  18.             merged.add(lastLeft);
  19.             merged.add(firstRight);
  20.         } else {
  21.             merged.add(Range.join(lastLeft, firstRight));
  22.         }
  23.         merged.addAll(right);
  24.  
  25.         merged.stream()
  26.               .map(Range::toRegex)
  27.               .forEach(System.out::println);
  28.     }
  29.  
  30.     private static LinkedList<Range> leftBounds(int start, int end) {
  31.         final LinkedList<Range> result = new LinkedList<>();
  32.         while (start < end) {
  33.             final Range range = Range.fromStart(start);
  34.             result.add(range);
  35.             start = range.getEnd()+1;
  36.         }
  37.         return result;
  38.     }
  39.  
  40.     private static LinkedList<Range> rightBounds(int start, int end) {
  41.         final LinkedList<Range> result = new LinkedList<>();
  42.         while (start < end) {
  43.             final Range range = Range.fromEnd(end);
  44.             result.add(range);
  45.             end = range.getStart()-1;
  46.         }
  47.         Collections.reverse(result);
  48.         return result;
  49.     }
  50.  
  51. }
  52.  
  53. class Range {
  54.     private final int start;
  55.     private final int end;
  56.  
  57.     public static Range fromEnd(int end) {
  58.         final char[] chars = String.valueOf(end).toCharArray();
  59.         for (int i=chars.length-1; i>=0;i--) {
  60.             if (chars[i] == '9') {
  61.                 chars[i] = '0';
  62.             } else {
  63.                 chars[i] = '0';
  64.                 break;
  65.             }
  66.         }
  67.  
  68.         return new Range(Integer.parseInt(String.valueOf(chars)), end);
  69.     }
  70.  
  71.     public static Range fromStart(int start) {
  72.         final char[] chars = String.valueOf(start).toCharArray();
  73.         for (int i=chars.length-1; i>=0;i--) {
  74.             if (chars[i]=='0') {
  75.                 chars[i] = '9';
  76.             } else {
  77.                 chars[i] = '9';
  78.                 break;
  79.             }
  80.         }
  81.  
  82.         return new Range(start, Integer.parseInt(String.valueOf(chars)));
  83.     }
  84.  
  85.     public static Range join(Range a, Range b) {
  86.         return new Range(a.start, b.end);
  87.     }
  88.  
  89.     private Range(int start, int end) {
  90.         this.start = start;
  91.         this.end = end;
  92.     }
  93.  
  94.     public int getStart() {
  95.         return start;
  96.     }
  97.  
  98.     public int getEnd() {
  99.         return end;
  100.     }
  101.  
  102.     public boolean overlaps(Range r) {
  103.         return end > r.start && r.end > start;
  104.     }
  105.  
  106.     @Override
  107.     public String toString() {
  108.         return String.format("Range{start=%d, end=%d}", start, end);
  109.     }
  110.  
  111.     public String toRegex() {
  112.         String startStr = String.valueOf(getStart());
  113.         String endStr = String.valueOf(getEnd());
  114.  
  115.         final StringBuilder result = new StringBuilder();
  116.  
  117.         for (int pos = 0; pos < startStr.length(); pos++) {
  118.             if (startStr.charAt(pos) == endStr.charAt(pos)) {
  119.                 result.append(startStr.charAt(pos));
  120.             } else {
  121.                 result.append('[')
  122.                       .append(startStr.charAt(pos))
  123.                       .append('-')
  124.                       .append(endStr.charAt(pos))
  125.                       .append(']');
  126.             }
  127.         }
  128.         return result.toString();
  129.     }
  130. }
  131.  
Success #stdin #stdout 0.23s 2841600KB
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45 583
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4[5-9]
[5-9][0-9]
[1-4][0-9][0-9]
5[0-7][0-9]
58[0-3]
https://ideone.com/j1Mh4c
language:
Java (HotSpot 12)
created:
7 years ago
visibility:
public

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