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  1. import java.util.*;
  2. import java.lang.*;
  3. import java.io.*;
  4.  
  5. // Problem Description: 
  6. // Reorder the digits of a number, in order to 
  7. // get the least one which is greater than the input number
  8.  
  9. class Ideone
  10. {
  11. 	public static String getLeastGreaterNumber(String number) {
  12. 		List<Character> decreasingChars = new ArrayList();
  13. 		int firstDecreasing = getDecreasingChars(number, decreasingChars);
  14.  
  15. 		if(isGreatestNumber(firstDecreasing)) {
  16. 			return "";
  17. 		}
  18.  
  19. 		String prefix = "";
  20. 		if(firstDecreasing > 1) {
  21. 			prefix = number.substring(0, firstDecreasing - 1);
  22. 		}
  23.  
  24. 		StringBuilder resultBuilder = new StringBuilder(prefix);
  25.  
  26. 		char target = number.charAt(firstDecreasing - 1);
  27. 		char leastGreater = swapLeastGreater(decreasingChars, target);
  28. 		resultBuilder.append(leastGreater);
  29.  
  30. 		Collections.sort(decreasingChars);
  31. 		appendList(resultBuilder, decreasingChars);
  32.  
  33. 		return resultBuilder.toString();
  34. 	}
  35.  
  36. 	private static Boolean isGreatestNumber(int firstDecreasing) {
  37. 		return firstDecreasing == 0;
  38. 	}
  39.  
  40. 	private static int getDecreasingChars(String number, List<Character> decreasing) {
  41. 		int firstDecreasing = number.length() - 1;
  42.  
  43. 		for(; firstDecreasing > 0; --firstDecreasing) {
  44. 			char curChar = number.charAt(firstDecreasing);
  45. 			char preChar = number.charAt(firstDecreasing - 1);
  46. 			decreasing.add(curChar);
  47.  
  48. 			if(curChar > preChar) {
  49. 				break;
  50. 			}
  51. 		}
  52.  
  53. 		return firstDecreasing;
  54. 	}
  55.  
  56. 	private static char swapLeastGreater(List<Character> chars, char target) {
  57. 		Iterator it=chars.iterator();
  58. 		char finding = '9';
  59. 		while(it.hasNext()) {
  60. 			char value = ((Character)it.next()).charValue();
  61. 			if(value > target && value < finding) {
  62. 				finding = value;
  63. 			}
  64. 		}
  65.  
  66. 		chars.remove(new Character(finding));
  67. 		chars.add(new Character(target));
  68.  
  69. 		return finding;
  70. 	}
  71.  
  72. 	private static void appendList(StringBuilder str, List<Character> chars) {
  73. 		Iterator it=chars.iterator();
  74. 		while(it.hasNext()) {
  75. 			char value = ((Character)it.next()).charValue();
  76. 			str.append(value);
  77. 		}
  78. 	}
  79.  
  80. 	//////////////////////////////////////////////////////////////
  81. 	// Test Code Begins
  82. 	//////////////////////////////////////////////////////////////
  83. 	private static void test(String number, String expected) {
  84. 		String result = getLeastGreaterNumber(number);
  85. 		if(result.equals(expected)) {
  86. 			System.out.println("Test passed with number " + number);
  87. 		}
  88. 		else {
  89. 			System.out.println("Test FAILED with number " + number);
  90. 		}
  91. 	}
  92.  
  93. 	private static void test1() {
  94. 		String number = "38276";
  95. 		String expected = "38627";
  96. 		test(number, expected);
  97. 	}
  98.  
  99. 	private static void test2() {
  100. 		String number = "34722641";
  101. 		String expected = "34724126";
  102. 		test(number, expected);
  103. 	}
  104.  
  105. 	private static void test3() {
  106. 		String number = "12345";
  107. 		String expected = "12354";
  108. 		test(number, expected);
  109. 	}
  110.  
  111. 	private static void test4() {
  112. 		String number = "987654";
  113. 		String expected = "";
  114. 		test(number, expected);
  115. 	}
  116.  
  117. 	private static void test5() {
  118. 		String number = "6";
  119. 		String expected = "";
  120. 		test(number, expected);
  121. 	}
  122.  
  123. 	private static void test6() {
  124. 		String number = "111111";
  125. 		String expected = "";
  126. 		test(number, expected);
  127. 	}
  128.  
  129. 	private static void test7() {
  130. 		String number = "111222333";
  131. 		String expected = "111223233";
  132. 		test(number, expected);
  133. 	}
  134.  
  135. 	private static void test8() {
  136. 		String number = "333222111";
  137. 		String expected = "";
  138. 		test(number, expected);
  139. 	}
  140.  
  141. 	private static void test9() {
  142. 		String number = "8987654321";
  143. 		String expected = "9123456788";
  144. 		test(number, expected);
  145. 	}
  146.  
  147. 	public static void main (String[] args) {
  148. 		test1();
  149. 		test2();
  150. 		test3();
  151. 		test4();
  152. 		test5();
  153. 		test6();
  154. 		test7();
  155. 		test8();
  156. 		test9();
  157. 	}
  158. }
Success #stdin #stdout 0.08s 380160KB
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stdin
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Standard input is empty
stdout
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Test passed with number 38276
Test passed with number 34722641
Test passed with number 12345
Test passed with number 987654
Test passed with number 6
Test passed with number 111111
Test passed with number 111222333
Test passed with number 333222111
Test passed with number 8987654321
https://ideone.com/czs13W
Get the next number with the given digits
language:
Java (HotSpot 12)
created:
10 years ago
visibility:
public

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