array of integers,return true if there are 2 consecutive numbers which are 7 or there are two 7s separated by a number . Using Java Streams only

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英文:

array of integers,return true if there are 2 consecutive numbers which are 7 or there are two 7s separated by a number . Using Java Streams only

问题

  1. import java.util.stream.IntStream;
  3. public class Main {
  4.     public static void main(String[] args) {
  5.         Integer a[] = { 1, 2, 1, 7, 3, 5, 2, 7 };
  6.         boolean flag = IntStream.range(0, a.length - 1)
  7.                 .anyMatch(i -> (a[i] == 7 && a[i + 1] == 7) || (i < a.length - 2 && a[i] == 7 && a[i + 2] == 7));
  8.         System.out.println(flag);
  9.     }
  10. }
英文: 
  1. Given an array of integers, return true if the array contains two 7&#39;s next to each other, or there are two 7&#39;s separated by one element. **Using Java Streams only**
  2. Example1: [1, 7, 7] → true
  3. Example2: [1, 7, 1, 7] → true
  4. Example3: [1, 7, 1, 1, 7] → false
  5. Example4: [7, 7, 1, 1, 7] → true
  6. Example5: [9, 0, 5, 1, 7] → false
  7. Example6: [7, 7, 7, 7, 7] → true

Please help, i am able to solve this using regular for loop, but i need the solution in java Streams

  1. public void static void main(String[] args) {
  2. 		Integer a[] = { 1, 2, 1, 7, 3, 5, 2, 7 };
  3. 		boolean flag = false;
  4. 		for (int i = 0; i &lt; a.length - 1; i++) {
  5. 			if (a[i] == 7 &amp;&amp; a[i + 1] == 7 || a[i] == 7 &amp;&amp; a[i + 1] == 1 &amp;&amp; a[i + 2] == 7) {
  6. 				flag = true;
  7. 			}
  8. 		}
  9. 		System.out.println(flag);
  10. 	}

//is it possible to avoid the for loop, and solve this using java streams –

答案1

得分: 1

以下是翻译好的内容：

这里是一个非常基本的答案。可能不是最聪明的解决方案，但我一时想不到更好的办法。

  1. IntStream.range(0, a.length-1)
  2.          .anyMatch( i -> a[i] == 7 && a[i+1] == 7 || a[i] == 7 
  3.                     && a[i + 1] == 1 && a[i + 2] == 7 );

下次请直接在问题中提供您的代码，这样可以更容易地帮助您。

英文:

Here's a very basic answer. It might not be the smartest solution but i can't think of anything better on the spot.

  1. IntStream.range(0, a.length-1)
  2.          .anyMatch( i -&gt; a[i] == 7 &amp;&amp; a[i+1] ==7 || a[i] == 7 
  3.                     &amp;&amp; a[i + 1] == 1 &amp;&amp; a[i + 2] == 7 );

And please next time provide your code in the question itself, to make helping you easier.

答案2

得分: 0

  1. // 使用流来实现，您可以编写一个自定义的 Collector，并像这样使用：
  3. // 对于 int[]
  4. boolean flag = Arrays.stream(arr).boxed().collect(TwoSevens.collector());
  6. // 对于 Integer[]
  7. boolean flag = Arrays.stream(arr).collect(TwoSevens.collector());
  9. // 对于 List<Integer>
  10. boolean flag = list.stream().collect(TwoSevens.collector());
  12. class TwoSevens {
  13.     public static Collector<Integer, ?, Boolean> collector() {
  14.         return Collector.of(TwoSevens::new, TwoSevens::add,
  15.                 (a,b) -> { throw new UnsupportedOperationException("Parallel processing not supported"); },
  16.                 TwoSevens::getResult);
  17.     }
  18.     private int prev1, prev2;
  19.     private boolean result;
  20.     private TwoSevens() {/*nothing to do*/}
  21.     private void add(int value) {
  22.         if (value == 7 && (prev1 == 7 || prev2 == 7))
  23.             this.result = true;
  24.         prev1 = prev2;
  25.         prev2 = value;
  26.     }
  27.     private boolean getResult() {
  28.         return this.result;
  29.     }
  30. }
  32. // 测试
  34. int[][] tests = { { 1, 7, 7 },
  35.                   { 1, 7, 1, 7 },
  36.                   { 1, 7, 1, 1, 7 },
  37.                   { 7, 7, 1, 1, 7 },
  38.                   { 9, 0, 5, 1, 7 },
  39.                   { 7, 7, 7, 7, 7 } };
  40. for (int[] arr : tests) {
  41.     boolean flag = Arrays.stream(arr).boxed().collect(TwoSevens.collector());
  42.     System.out.println(Arrays.toString(arr) + ": " + flag);
  43. }
  45. // 输出
  47. [1, 7, 7]: true
  48. [1, 7, 1, 7]: true
  49. [1, 7, 1, 1, 7]: false
  50. [7, 7, 1, 1, 7]: true
  51. [9, 0, 5, 1, 7]: false
  52. [7, 7, 7, 7, 7]: true
英文:

To do it with streams, you can write a custom Collector, and use it like this:

  1. // With an int[]
  2. boolean flag = Arrays.stream(arr).boxed().collect(TwoSevens.collector());
  4. // With an Integer[]
  5. boolean flag = Arrays.stream(arr).collect(TwoSevens.collector());
  7. // With a List&lt;Integer&gt;
  8. boolean flag = list.stream().collect(TwoSevens.collector());
  1. class TwoSevens {
  2. 	public static Collector&lt;Integer, ?, Boolean&gt; collector() {
  3. 		return Collector.of(TwoSevens::new, TwoSevens::add,
  4. 				(a,b) -&gt; { throw new UnsupportedOperationException(&quot;Parallel processing not supported&quot;); },
  5. 				TwoSevens::getResult);
  6. 	}
  7. 	private int prev1, prev2;
  8. 	private boolean result;
  9. 	private TwoSevens() {/*nothing to do*/}
  10. 	private void add(int value) {
  11. 		if (value == 7 &amp;&amp; (prev1 == 7 || prev2 == 7))
  12. 			this.result = true;
  13. 		prev1 = prev2;
  14. 		prev2 = value;
  15. 	}
  16. 	private boolean getResult() {
  17. 		return this.result;
  18. 	}
  19. }

Test

  1. int[][] tests = { { 1, 7, 7 },
  2.                   { 1, 7, 1, 7 },
  3.                   { 1, 7, 1, 1, 7 },
  4.                   { 7, 7, 1, 1, 7 },
  5.                   { 9, 0, 5, 1, 7 },
  6.                   { 7, 7, 7, 7, 7 } };
  7. for (int[] arr : tests) {
  8. 	boolean flag = Arrays.stream(arr).boxed().collect(TwoSevens.collector());
  9. 	System.out.println(Arrays.toString(arr) + &quot;: &quot; + flag);
  10. }

Output

  1. [1, 7, 7]: true
  2. [1, 7, 1, 7]: true
  3. [1, 7, 1, 1, 7]: false
  4. [7, 7, 1, 1, 7]: true
  5. [9, 0, 5, 1, 7]: false
  6. [7, 7, 7, 7, 7]: true

答案3

得分: 0

可能是一个不正统的方法来处理这个任务，但是将数字转换为字符串然后使用正则表达式如何？

  1. public void static void main(String[] args) {
  2.     Integer a[] = { 1, 2, 1, 7, 3, 5, 2, 7 };
  3.     boolean flag = Arrays.stream(a)
  4.                          .map(String::valueOf)
  5.                          .collect(Collectors.joining())
  6.                          .matches("\\d*77\\d*|\\d*7\\d7\\d*");
  7.     System.out.println(flag);
  8. }
英文:

Probably an unorthodox way to approach this task but how about converting the numbers to string and using regex?

  1. public void static void main(String[] args) {
  2.     Integer a[] = { 1, 2, 1, 7, 3, 5, 2, 7 };
  3.     boolean flag = Arrays.stream(a)
  4.                          .map(String::valueOf)
  5.                          .collect(Collectors.joining())
  6.                          .matches(&quot;\\d*77\\d*|\\d*7\\d7\\d*&quot;);
  7.     System.out.println(flag);
  8. }

huangapple
  • 本文由 发表于 2020年10月12日 16:26:35
  • 转载请务必保留本文链接：https://go.coder-hub.com/64314207.html
  • java
  • java-stream
  • stream
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