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Certification: Intermediate Level Accuracy: 0% Submissions: 8 Points: 10

Write a C program to find the first and last position of a given target value in a sorted array. If the target is not found in the array, return [-1, -1]. The algorithm must run in O(log n) time complexity.

Example 1
    
  
  • Input: nums = [5, 7, 7, 8, 8, 10], target = 8
    • 
  
  • Output: [3, 4]
    • 
  
  • Explanation: 
    • Step 1: The target value 8 appears at indices 3 and 4.

    • Step 2: First occurrence is at index 3.

    • Step 3: Last occurrence is at index 4.

    • Step 4: Therefore, return [3, 4].
    •
Example 2
    
  
  • Input: nums = [5, 7, 7, 8, 8, 10], target = 6
    • 
  
  • Output: [-1, -1]
    • 
  
  • Explanation: 
    • Step 1: The target value 6 is not present in the array.

    • Step 2: Since target is not found, return [-1, -1].

    • Step 3: This indicates that the target has no first or last position.
    •
Constraints
    
  
  • 0 ≤ nums.length ≤ 10^5
    • 
  
  • -10^9 ≤ nums[i] ≤ 10^9
    • 
  
  • nums is a non-decreasing array
    • 
  
  • -10^9 ≤ target ≤ 10^9
    • 
  
  • Time Complexity: O(log n)
    • 
  
  • Space Complexity: O(1)
    •
ArraysAlgorithmsDeloitteAdobe
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Hint
Solution

Solution Hints

    
  
  • Use binary search to find the first occurrence of the target.
    • 
  
  • Use binary search to find the last occurrence of the target.
    • 
  
  • Modify the standard binary search to find leftmost position.
    • 
  
  • Modify the standard binary search to find rightmost position.
    • 
  
  • Return [-1, -1] if target is not found in either search.
    •

Steps to solve by this approach:

 Step 1: Create a helper function to find the first occurrence using modified binary search.
 Step 2: In the first search, when target is found, continue searching left to find the leftmost occurrence.
 Step 3: Create another helper function to find the last occurrence using modified binary search.
 Step 4: In the second search, when target is found, continue searching right to find the rightmost occurrence.
 Step 5: Handle edge cases where the array is empty or target is not found.
 Step 6: Return the results in an array format [first_position, last_position].
 Step 7: Use proper memory allocation for the result array.

Submitted Code :