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Life-coding

Solve one problem everyday.

All of my daily problem solving lives in this repo. Some of the wrong attempt is also here. If you follow this repo, make sure you run the code and try with test cases.

Resources

  1. Cracking the coding interview book
  2. https://www.geeksforgeeks.org/
  3. https://www.interviewbit.com/practice/
  4. https://start.interviewing.io/dashboard/interviewee
  5. https://leetcode.com/
  6. https://www.coursera.org/
  7. https://code.google.com/codejam/kickstart/
  8. https://www.pramp.com/dashboard
  9. https://www.youtube.com/channel/UCWSYAntBbdd2SLYUqPIxo0w
  10. https://www.byte-by-byte.com/
  11. https://www.dailycodingproblem.com/
  12. https://coderbyte.com/
  13. https://www.interviewcake.com
  14. https://www.geeksforgeeks.org/must-do-coding-questions-for-companies-like-amazon-microsoft-adobe/
  15. https://www.programcreek.com/2012/11/top-10-algorithms-for-coding-interview/

Helper materials:

Tree:

  1. Segment Tree: https://www.youtube.com/watch?v=Oq2E2yGadnU
  2. AVL Tree: https://www.youtube.com/watch?v=-9sHvAnLN_w

Understanding SSTable

1. https://www.igvita.com/2012/02/06/sstable-and-log-structured-storage-leveldb/
2. https://hackernoon.com/fundamentals-of-system-design-part-3-8da61773a631

Java Code Beauty:

Composition Function: http://www.deadcoderising.com/2015-09-07-java-8-functional-composition-using-compose-and-andthen/

Quick Notes

Counting character frequency in a string.

String s="HelloWorld";
Map<Character, Long> map = t.chars() //converting int stream
                  .mapToObj(c -> (char) c)//int stream to character stream
                  .collect(Collectors.groupingBy(Function.identity(),// collect by group
                          Collectors.counting()));
          System.out.println(map);

Best way to find mid point.

M=start+(end-start)/2;//overflow error free

Sort an int array in descending order

int[] sorted = IntStream.of(inputArray)
        .boxed()
        .sorted(Comparator.reverseOrder())
        .mapToInt(i -> i)
        .toArray();

Iterating over map

map.entrySet().stream().forEach(entry->{
          System.out.println("Key: "+entry.getKey()+"value: "+entry.getValue());
      });

String counting in java 8

        String[] strings=new String[]{"hello","world","hello"};
        List<String> list=Arrays.asList(strings);
        Map<String, Long> map1=         list.stream().collect(groupingBy(identity(), counting()));

Sort list of object based on property

 private static class Inerval {
        int start;
        int end;

        public Inerval(int start, int end) {
            this.start = start;
            this.end = end;
        }
    }
    
     ArrayList<Inerval> list=new ArrayList<>();
     list.add(new Inerval(1,3));
     list.add(new Inerval(5,8));
     list.add(new Inerval(4,10));
     list.add(new Inerval(20,25));
     list.sort(Comparator.comparingInt(v -> v.start));
     list.stream().forEach(interval -> {
                System.out.println(interval.start+"->"+interval.end);
      });

PriorityQueue with custom comparator

 PriorityQueue<ListNode> pq = new PriorityQueue<>(Comparator.comparing(node -> node.val));