Minimum Number of Days to Make m Bouquets

Minimum Number of Days to Make m Bouquets is a Medium Data Structures and Algorithms interview problem you can solve, run and submit on Thita.ai. It belongs to the Binary Search Patterns pattern, in the On Answer / Condition Function subpattern.

Problem statement

You are given an integer array bloomDay, an integer m and an integer k.

You want to make m bouquets. To make a bouquet, you need to use k adjacent flowers from the garden.

The garden consists of n flowers, the ith flower will bloom in the bloomDay[i] and then can be used in exactly one bouquet.

Return the minimum number of days you need to wait to be able to make m bouquets from the garden. If it is impossible to make m bouquets return -1.

Example 1:

Input: bloomDay = [1,10,3,10,2], m = 3, k = 1 Output: 3 Explanation: Let us see what happened in the first three days. x means flower bloomed and means flower did not bloom in the garden. We need 3 bouquets each should contain 1 flower. After day 1: [x, , , , ] // we can only make one bouquet. After day 2: [x, , , , x] // we can only make two bouquets. After day 3: [x, , x, , x] // we can make 3 bouquets. The answer is 3.

Example 2:

Input: bloomDay = [1,10,3,10,2], m = 3, k = 2 Output: -1 Explanation: We need 3 bouquets each has 2 flowers, that means we need 6 flowers. We only have 5 flowers so it is impossible to get the needed bouquets and we return -1.

Example 3:

Input: bloomDay = [7,7,7,7,12,7,7], m = 2, k = 3 Output: 12 Explanation: We need 2 bouquets each should have 3 flowers. Here is the garden after the 7 and 12 days: After day 7: [x, x, x, x, , x, x] We can make one bouquet of the first three flowers that bloomed. We cannot make another bouquet from the last three flowers that bloomed because they are not adjacent. After day 12: [x, x, x, x, x, x, x] It is obvious that we can make two bouquets in different ways.

Constraints:

- bloomDay.length == n

- 1 <= n <= 105

- 1 <= bloomDay[i] <= 109

- 1 <= m <= 106

- 1 <= k <= n

Topics and companies

Topics: Array, Binary Search.

Reported in interviews at Google.

How to practise Minimum Number of Days to Make m Bouquets on Thita.ai

Starter code is provided in C, C#, C++, Go, Java, JavaScript and Python. Your solution runs against 5 test cases for this problem, with the AI coach available for a hint when you are stuck rather than a finished answer. The reference solution runs in O(nlogd), d is the max day of bloomDay time and O(1) space.

Open Minimum Number of Days to Make m Bouquets in the code editor, or read the Minimum Number of Days to Make m Bouquets editorial for a worked solution with its approach and complexity analysis.

Where Minimum Number of Days to Make m Bouquets sits in the DSA pattern sheet

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