[Announce] Week 2 homework

[Pyohwan]

Week 2 homework

• Article reading and make a word list
• Weekly speaking topic : Coding problem (pick one)
  • How do you find the missing number in a given integer array of 1 to 100?
  • How are all leaves of a binary search tree printed?

[silverprize]

good luck

[Pyohwan]

Word list

• probability : 1. 개연성 2. 개연성 있는 일 3. 확률
  • It meets garbage collection (GC) pause time goals with high probability
• contiguous : 인접한, 근접한
  • The heap is partitioned into a set of equal-sized heap regions, each a contiguous range of virtual memory.
• prediction : 1. 예언,예측,예언된 일 2. 예보
• based on : ~에 근거하여
  • G1 uses a pause prediction model to meet a user-defined pause time target and selects the number of regions to collect based on the specified pause time target.
• ripe : 1. 익은 2. 숙성한 3. 고약한
  • The regions identified by G1 as ripe for reclamation are garbage collected using evacuation.
• meet : 충족
  • It meets the set pause time target with high probability but not absolute certainty.
• Applications running today
  • Applications running today with either the CMS or the ParallelOld garbage collector would benefit switching to G1 if the application has one or more of the following traits.
• sufficiently : 충분히, (…하기에) 충분할 만큼 ((to do))
• fine-grained : 1. <석재·목재 등이> 결이 고운 2. = FINE-GRAIN
  • G1 compacts sufficiently to completely avoid the use of fine-grained free lists for allocation, and instead relies on regions.
  • 독해 쉽지 않음.
• considerably : 많이, 상당히
  • This considerably simplifies parts of the collector, and mostly eliminates potential fragmentation issues.

Coding problem

• How do you find the missing number in a given integer array of 1 to 100?

  Analysis Requirements

• As I understand it, I get an array of numbers from 1 to 100. Find an integer missing between lowest and highest numbers in the array.
• Need to return integer array.

• Verification process of input integer array is necessary. For example, integers between 1 and 100 should not be included in the array.

  Code

  public class FindMissingNumberTests {
  
  @Test
  public void fineMissingNumbers() {
      Assert.assertEquals(Arrays.asList(5,7,8,9), this.getMissingNumbers(Arrays.asList(1,10,2,3,6,4)));
      Assert.assertEquals(Arrays.asList(11,12,13,15,17,18,20), this.getMissingNumbers(Arrays.asList(10,19,21,16,14,10)));
  
  }
  
  private List<Integer> getMissingNumbers(List<Integer> numbers) {
  
      // sort and distinct
      List<Integer> sourceNumbers = numbers.stream().sorted().distinct().collect(Collectors.toList());
  
      Integer firstNumber = sourceNumbers.get(0);
      Integer lastNumber = sourceNumbers.get(sourceNumbers.size() -1);
  
      // verify numbers are between 0 ~ 100.
      if (firstNumber < 0 || lastNumber > 100) {
          throw new IllegalArgumentException("Number must be be between 0 and 100.");
      }
  
      List<Integer> missingNumbers = new ArrayList<>();
      Integer sourceNumbersIdx = 0;
  
      // Loop from smallest to largest number of sourceNumbers with fullCount.
      // If value of sourceNumbers is not equal to fullCount, It is missing number.
      for (Integer fullCount = firstNumber ; fullCount <= lastNumber ; fullCount++) {
          Integer getCleanedNumber = sourceNumbers.get(sourceNumbersIdx);
  
          if (getCleanedNumber.equals(fullCount)) {
              sourceNumbersIdx++;
          } else if (! getCleanedNumber.equals(fullCount)) {
              missingNumbers.add(fullCount);
          }
      }
  
      // Could not do foreach fully.
      if (sourceNumbersIdx < sourceNumbers.size() -1) {
          throw new RuntimeException("Could not do foreach fully.");
      }
  
      return missingNumbers;
  }
  }