Copleted 1 problem

[lakshmidurgat]

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[super30admin]

Interview Problem: Find Missing Number in a sorted array (Problem1.java)

Your solution attempts a binary search approach, which is the right idea for O(log n) performance. However, there are several issues to address:

1. Fix compilation errors first:

   • Replace hi with h (the parameter name)
   • Make leftBinarySearch and rightBinarySearch static so they can be called from the static missingNumber method
   • Add bounds checks: if (mid > 0 && arr[mid-1] + 1 != arr[mid]) and if (mid < arr.length - 1 && arr[mid+1] - 1 != arr[mid])

2. Simplify your approach: Instead of two separate binary searches, use a single binary search based on the difference between value and index. The reference solution elegantly uses arr[i] - i — if all numbers were present, this difference would be constant. When the difference changes, you've found the missing region.

3. Cleaner implementation suggestion:

static int missingNumber(int[] arr) {
    int low = 0, high = arr.length - 1;
    while (high - low > 1) {
        int mid = low + (high - low) / 2;
        if (arr[low] - low != arr[mid] - mid)
            high = mid;
        else
            low = mid;
    }
    return arr[low] + 1;
}

4. Naming conventions: Use descriptive variable names like low and high instead of single letters, and fix typos in method names.

5. Test edge cases: Consider what happens when the missing number is at the beginning or end of the array.

VERDICT: NEEDS_IMPROVEMENT

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Interview Problem: Design Min Heap

Your submission does not address the problem at all. The problem requires you to implement a Min Heap data structure with the following operations:

1. getMin(): Returns the root element in O(1)
2. extractMin(): Removes and returns the minimum element in O(log N)
3. insert(): Adds a new key while maintaining heap property in O(log N)

Your code appears to be a solution for a different problem (finding a missing number in an array). Additionally, your code has several compilation errors:

• Using hi instead of h in the binary search methods
• Missing return statements in some methods
• Mixing static and non-static method declarations
• Incorrect logic for the missing number problem

Please re-read the problem carefully and implement a Min Heap using an array-based approach. You'll need:

• An array to store heap elements
• Helper methods to calculate parent and child indices (parent = (i-1)/2, left child = 2i+1, right child = 2i+2)
• A heapify method to maintain the heap property after removal
• An insert method that adds elements and bubbles up
• An extractMin method that removes the root and heapifies down

VERDICT: NEEDS_IMPROVEMENT