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  1. import java.time.Month;
  2. import java.util.Arrays;
  3. import java.util.stream.Collectors;
  4. import java.util.stream.IntStream;
  5.  
  6. class Main {
  7.  
  8. 	public static void main(String[] args) {
  9. 		var main = new Main();
  10. 		// 各配列は、Comparableを継承している必要がある。
  11. 		// Comparableを継承している型の配列であれば、なんでも扱える
  12. 		main.printNewIndexs(new Integer[] { 1, 100, 10, 10000, 1000 });
  13. 		main.printNewIndexs(new Integer[] { 3, 1, 4, 1, 5, 9, 2 });
  14. 		main.printNewIndexs(new Integer[] { 0, 1, 0, 1, 0, 1, 0, 1 });
  15. 		main.printNewIndexs(new String[] { "A", "C", "B", "E", "D" });
  16. 		main.printNewIndexs(new Month[] { Month.MARCH, Month.JANUARY, Month.APRIL, Month.JANUARY, Month.MAY, Month.SEPTEMBER, Month.FEBRUARY });
  17. 	}
  18.  
  19. 	private <T extends Comparable<T>> void printNewIndexs(T[] values) {
  20. 		var newIndexs = makeNewIndexs(values);
  21. 		System.out.println(Arrays.toString(newIndexs));
  22. 	}
  23.  
  24. 	private <T extends Comparable<T>> int[] makeNewIndexs(T[] values) {
  25. //		record ValueWithIndex<T extends Comparable<T>>(int index, T value) implements Comparable<ValueWithIndex<T>> {
  26. //			@Override
  27. //			public int compareTo(ValueWithIndex<T> o) {
  28. //				return value.compareTo(o.value);
  29. //			}
  30. //    	
  31. //	    }
  32. 		// recordはTでも通ったが、classは一部をT以外にしないと通らない
  33. 		class ValueWithIndex<U extends Comparable<U>> implements Comparable<ValueWithIndex<T>> {
  34. 			final int index;	// 元のindex情報が必要
  35. 			final T value;
  36. 			ValueWithIndex(int index, T value) {
  37. 				this.index = index;
  38. 				this.value = value;
  39. 			}
  40. 			@Override
  41. 			public int compareTo(ValueWithIndex<T> o) {
  42. 				return value.compareTo(o.value);
  43. 			}
  44. 		}
  45. 		var sortedList = IntStream.range(0, values.length)
  46. 				.mapToObj(index -> new ValueWithIndex<T>(index, values[index]))
  47. 				.sorted()
  48. //				.toList();
  49. 				.collect(Collectors.toList());
  50. 		var newIndexs = new int[sortedList.size()];
  51. 		IntStream.range(0, sortedList.size())
  52. 		.forEach(index -> newIndexs[sortedList.get(index).index] = index);
  53. 		return newIndexs;
  54. 	}
  55.  
  56. }
  57.  
Success #stdin #stdout 0.09s 54480KB
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stdin
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Standard input is empty
stdout
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[0, 2, 1, 4, 3]
[3, 0, 4, 1, 5, 6, 2]
[0, 4, 1, 5, 2, 6, 3, 7]
[0, 2, 1, 4, 3]
[3, 0, 4, 1, 5, 6, 2]
https://ideone.com/BV5FXe
language:
Java (HotSpot 12)
created:
47 days ago
visibility:
secret

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