Introduction

In this blog post, we will explore how to solve the LeetCode problem "1521" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like Chatmagic, we can generate solutions quickly and efficiently - helping you pass the interviews and get the job offer without having to study for months.

Problem Statement

Winston was given the above mysterious function func. He has an integer array arr and an integer target and he wants to find the values l and r that make the value |func(arr, l, r) - target| minimum possible. Return the minimum possible value of |func(arr, l, r) - target|. Notice that func should be called with the values l and r where 0 <= l, r < arr.length. Example 1: Input: arr = [9,12,3,7,15], target = 5 Output: 2 Explanation: Calling func with all the pairs of [l,r] = [[0,0],[1,1],[2,2],[3,3],[4,4],[0,1],[1,2],[2,3],[3,4],[0,2],[1,3],[2,4],[0,3],[1,4],[0,4]], Winston got the following results [9,12,3,7,15,8,0,3,7,0,0,3,0,0,0]. The value closest to 5 is 7 and 3, thus the minimum difference is 2. Example 2: Input: arr = [1000000,1000000,1000000], target = 1 Output: 999999 Explanation: Winston called the func with all possible values of [l,r] and he always got 1000000, thus the min difference is 999999. Example 3: Input: arr = [1,2,4,8,16], target = 0 Output: 0 Constraints: 1 <= arr.length <= 105 1 <= arr[i] <= 106 0 <= target <= 107

Explanation

Here's a breakdown of the approach, followed by the code:

• Iterate and Calculate: Iterate through all possible subarrays defined by l and r indices within the given array arr. For each subarray, calculate the result of the bitwise AND operation (func in the prompt) across the elements of the subarray.
• Minimize Difference: Keep track of the minimum absolute difference between the calculated bitwise AND result and the target value.

• Return Minimum: Return the minimized absolute difference.

• Runtime Complexity: O(n^2), Storage Complexity: O(1)

Code

    def solve():
    arr = [int(x) for x in input().split()]
    target = int(input())

    def func(arr, l, r):
        result = arr[l]
        for i in range(l + 1, r + 1):
            result &= arr[i]
        return result

    min_diff = float('inf')
    for l in range(len(arr)):
        for r in range(l, len(arr)):
            val = func(arr, l, r)
            min_diff = min(min_diff, abs(val - target))

    print(min_diff)

# arr = [9,12,3,7,15]
# target = 5
# solve()

# arr = [1000000,1000000,1000000]
# target = 1
# solve()

# arr = [1,2,4,8,16]
# target = 0
# solve()

def solve2(arr, target):

    def func(arr, l, r):
        result = arr[l]
        for i in range(l + 1, r + 1):
            result &= arr[i]
        return result

    min_diff = float('inf')
    for l in range(len(arr)):
        for r in range(l, len(arr)):
            val = func(arr, l, r)
            min_diff = min(min_diff, abs(val - target))

    return min_diff