Complete Problem9

[dhruvil15]

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[super30admin]

Find the First and Last Position of an Element in given Sorted Array (Problem10.java)

It seems there has been a misunderstanding. The problem you were asked to solve is "Find the First and Last Position of an Element in given Sorted Array", but your solution is for "Find Minimum in Rotated Sorted Array". These are two distinct problems.

For the correct problem, you need to implement two binary searches: one to find the first occurrence of the target and another to find the last occurrence. Your current solution does not take a target parameter and instead finds the minimum value in a rotated array.

Please revisit the problem statement and requirements. You'll need to write a function that accepts an array and a target value, then returns the start and end indices of that target value. The solution must run in O(log n) time complexity.

VERDICT: NEEDS_IMPROVEMENT

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Find the Minimum Element in a Rotated Array(sorted) (Problem11.java)

Dear student,

You have implemented a binary search solution for finding a peak element, which is a different problem. The problem you were asked to solve is about finding the minimum element in a rotated sorted array.

Key differences:

• In a rotated sorted array, the minimum element is the pivot point where the array breaks its ascending order.
• Your current solution looks for an element that is greater than its neighbors (a peak), which is not what we need here.

To correct your solution:

1. You need to compare the middle element with the rightmost element to determine which side the minimum is on.
2. If nums[mid] > nums[high], the minimum must be in the right half.
3. Otherwise, the minimum is in the left half (including mid).

Here's a corrected approach:

public int findMin(int[] nums) {
    int left = 0, right = nums.length - 1;
    while (left < right) {
        int mid = left + (right - left) / 2;
        if (nums[mid] > nums[right]) {
            left = mid + 1;
        } else {
            right = mid;
        }
    }
    return nums[left];
}

Please review the problem statement again and adjust your solution accordingly. Your binary search implementation shows good understanding, but you need to apply it to the correct problem.

VERDICT: NEEDS_IMPROVEMENT

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Find the Peak Element (Problem9.java)

Your code is well-written for the "Find First and Last Position of Element in Sorted Array" problem. However, it does not solve the "Find the Peak Element" problem. You may have confused the two problems.

For the peak element problem, you need to find an index where the element is greater than its neighbors. Since the problem requires logarithmic time complexity, you should use a binary search approach that compares the middle element with its neighbors to decide which half to search next.

Here are some tips for solving the peak element problem:

1. Check if the middle element is a peak (i.e., greater than both left and right neighbors). If yes, return its index.
2. If the right neighbor is greater than the middle element, then there must be a peak in the right half (because the right end is considered as negative infinity).
3. Similarly, if the left neighbor is greater, search the left half.

You can refer to the reference solution provided in the problem for guidance. Try to implement a binary search that adapts to these conditions.

VERDICT: NEEDS_IMPROVEMENT