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2392. Successful Pairs Of Spells And Potions

Array Two Pointers Binary Search Sorting

Problem - Successful Pairs Of Spells And Potions

Medium

You are given two positive integer arrays spells and potions, of length n and m respectively, where spells[i] represents the strength of the ith spell and potions[j] represents the strength of the jth potion.

You are also given an integer success. A spell and potion pair is considered successful if the product of their strengths is at least success.

Return an integer array pairs of length n where pairs[i] is the number of potions that will form a successful pair with the ith spell.

 

Example 1:

Input: spells = [5,1,3], potions = [1,2,3,4,5], success = 7
Output: [4,0,3]
Explanation:
- 0th spell: 5 * [1,2,3,4,5] = [5,10,15,20,25]. 4 pairs are successful.
- 1st spell: 1 * [1,2,3,4,5] = [1,2,3,4,5]. 0 pairs are successful.
- 2nd spell: 3 * [1,2,3,4,5] = [3,6,9,12,15]. 3 pairs are successful.
Thus, [4,0,3] is returned.

Example 2:

Input: spells = [3,1,2], potions = [8,5,8], success = 16
Output: [2,0,2]
Explanation:
- 0th spell: 3 * [8,5,8] = [24,15,24]. 2 pairs are successful.
- 1st spell: 1 * [8,5,8] = [8,5,8]. 0 pairs are successful. 
- 2nd spell: 2 * [8,5,8] = [16,10,16]. 2 pairs are successful. 
Thus, [2,0,2] is returned.

 

Constraints:

  • n == spells.length
  • m == potions.length
  • 1 <= n, m <= 105
  • 1 <= spells[i], potions[i] <= 105
  • 1 <= success <= 1010

Solutions

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class Solution:
    def successfulPairs(self, spells: List[int], potions: List[int], success: int) -> List[int]:
        potions.sort()
        n, m = len(spells), len(potions)
        result = [m - bisect_left(potions, success / val) for val in spells]
        return result

        # potions.sort()
        # n, m = len(spells), len(potions)
        # result = []
        # for i in range(n):
        #     left, right = 0, m - 1
        #     index = m

        #     while right >= left:
        #         mid = (left + right) // 2
        #         if spells[i] * potions[mid] >= success:
        #             index = mid
        #             right = mid - 1
        #         elif spells[i] * potions[mid] < success:
        #             left = mid + 1
        #     result.append(m - index)

        # return result

Submission Stats:

  • Runtime: 213 ms (83.90%)
  • Memory: 42.7 MB (43.37%)