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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10. public static void main(final String[] args) {
  11. 		//Your input of [[1,0],[2,0],[3,3],[1,0,0]] in a List of Lists
  12. 		final List<List<Integer>> input = createInput();
  13.  
  14. 		//To hold onto the groups for printing later
  15. 		final Map<Integer, List<List<Integer>>> groupsMap = new HashMap<Integer, List<List<Integer>>>();
  16.  
  17. 		//This will track the List<Integer> that have already been grouped.
  18. 		final List<List<Integer>> ungroupedLists = new ArrayList<List<Integer>>(input);
  19.  
  20. 		for (int i = 0; i < input.size(); i++ ) {
  21. 			//This gets the group indexed at i (starting from 0 just like arrays)
  22. 			final List<Integer> currentList = input.get(i);
  23.  
  24. 			//This checks if the currentList has already been grouped.
  25. 			//If it has, then continue to the next List.
  26. 			if( !ungroupedLists.contains(currentList) ) {
  27. 				continue;
  28. 			}
  29. 			//If it hasn't already been grouped, then remove it as we're going to group it now.
  30. 			ungroupedLists.remove(currentList);
  31.  
  32. 			//Create a new group to add any grouped lists to.
  33. 			final List<List<Integer>> currentGroup = new ArrayList<List<Integer>>();
  34. 			currentGroup.add(currentList);
  35.  
  36. 			//For the ungrouped lists, check if they group with the current list.
  37. 			for (int j = 0; j < ungroupedLists.size(); j++) {
  38. 				//Get the list we want to compare the current one to.
  39. 				final List<Integer> currentComparisonList = ungroupedLists.get(j);
  40.  
  41. 				//Gets the first integer of the currentList
  42. 				final Integer integer = currentList.get(0);
  43. 				//Gets the last integer of the currentList
  44. 				final Integer integer2 = currentList.get(currentList.size()-1);
  45. 				//Gets the first integer of the currentComparisonList
  46. 				final Integer integer3 = currentComparisonList.get(0);
  47. 				//Gets the last integer of the currentComparisonList
  48. 				final Integer integer4 = currentComparisonList.get(currentComparisonList.size()-1);
  49.  
  50. 				//If the first Integers match, and the last integers match, add the currentComparisonList
  51. 				//To the group and remove it from the ungroupedLists collection
  52. 				if( integer == integer3 && integer2 == integer4 ) {
  53. 					currentGroup.add(currentComparisonList);
  54. 					ungroupedLists.remove(currentComparisonList);
  55. 				}
  56. 			}
  57.  
  58. 			//When we've done all of that checking, add the group to the map of groups.
  59. 			groupsMap.put(i, currentGroup);
  60. 		}
  61.  
  62. 		//This simply prints the output int he format desired.
  63. 		for ( int i = 0; i < groupsMap.size(); i++ ) {
  64. 			System.out.println("group: " + i);
  65. 			for (final List<Integer> list : groupsMap.get(i)) {
  66. 				System.out.println(list.toString());
  67. 			}
  68. 		}
  69.  
  70. 	}
  71.  
  72. 	private static List<List<Integer>> createInput() {
  73. 		final List<List<Integer>> input = new ArrayList<List<Integer>>();
  74. 		final ArrayList<Integer> list1 = new ArrayList<Integer>();
  75. 		list1.add(1);
  76. 		list1.add(0);
  77. 		final ArrayList<Integer> list2 = new ArrayList<Integer>();
  78. 		list2.add(2);
  79. 		list2.add(0);
  80. 		final ArrayList<Integer> list3 = new ArrayList<Integer>();
  81. 		list3.add(3);
  82. 		list3.add(3);
  83. 		final ArrayList<Integer> list4 = new ArrayList<Integer>();
  84. 		list4.add(1);
  85. 		list4.add(0);
  86. 		list4.add(0);
  87. 		input.add(list1);
  88. 		input.add(list2);
  89. 		input.add(list3);
  90. 		input.add(list4);
  91. 		return input;
  92. 	}
  93. }
Success #stdin #stdout 0.07s 380224KB
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stdin
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Standard input is empty
stdout
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group: 0
[1, 0]
[1, 0, 0]
group: 1
[2, 0]
group: 2
[3, 3]
https://ideone.com/vO9fxD
language:
Java (HotSpot 12)
created:
12 years ago
visibility:
public

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