ServiceNow | Software Engineer | Hyderabad

Round 1: (DSA & Technical)

Questions:

• Given the following JavaScript code snippet, debug it:

  var temp = 'hi';
  function display() {
      console.log(temp);
      var temp = 'bye';
  };
  display();

• Follow-up question: What happens if var is replaced by let?

• Explain JavaScript hoisting.

• What is the Virtual DOM?

• DSA question: Given the array arr[] = {1, 6, 11, 16, 21, 31}; which has an arithmetic mean series, find the missing element (except the first and last).

  private static int func(int[] arr) {
      int i = 0;
      int len = arr.length;
      int diff = (arr[len - 1] - arr[0]) / (len);
      
      for(i = 0; i < len - 1; i++) {
          if(arr[i] + diff != arr[i + 1]) {
              break;
          }
      }
      
      return arr[i] + diff;
  }
  
  public static void main(String []args){
      int arr[]  = {1, 6, 11, 16, 21, 31};
      int res = func(arr);
      System.out.println(res);
  }

  • Time complexity: O(N)
  • Space complexity: O(1)

• Further optimization was requested, and the candidate explained a binary search approach.

  • Time complexity: O(log N)
  • Space complexity: O(1)

• Another DSA question: Count distinct occurrences as a subsequence.

  • Input: S = banana, T = ban, Output: 3
  • Input: S = Sosasossos, T = sos, Output: 6

• How does GitHub update code in real-time without refreshing?

Round 1: (DSA & Technical) - Update

Questions:

1. Product Array except self (LeetCode)
2. Median of Running data stream (LeetCode)
3. Design a counter in React JS with CSS that blocks increment/decrement actions for 5 seconds.