Minimum Operations to Collect Elements — LeetCode 2869 Python Solution

The problem

You are given an array nums of positive integers and an integer k. In one operation, you can remove the last element of the array and add it to your collection.

Example

Input

nums = [3,1,5,4,2], k = 2

Output

4

Explanation

After 4 operations, we collect elements 2, 4, 5, and 1, in this order. Our collection contains elements 1 and 2. Hence, the answer is 4.

Python solution

class Solution:
    def minOperations(self, nums: List[int], k: int) -> int:
        is_added = [False] * k
        count = 0
        n = len(nums)
        for i in range(n - 1, -1, -1):
            if nums[i] > k or is_added[nums[i] - 1]:
                continue
            is_added[nums[i] - 1] = True
            count += 1
            if count == k:
                return n - i

Complexity

Pattern: Bit Manipulation

Use XOR, masks and the low-bit trick to replace whole data structures with an integer. LeetCode 2869. Minimum Operations to Collect Elements is filed here because LeetCode tags it Bit Manipulation, which is the vocabulary this hub collects.

The bit manipulation guide has the Python template for the pattern and the 194 LeetCode problems that use it.

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