Watch 10 video solutions for Shortest Impossible Sequence of Rolls, a hard level problem involving Array, Hash Table, Greedy. This walkthrough by Ashish Pratap Singh has 1,002,241 views views. Want to try solving it yourself? Practice on FleetCode or read the detailed text solution.
You are given an integer array rolls of length n and an integer k. You roll a k sided dice numbered from 1 to k, n times, where the result of the ith roll is rolls[i].
Return the length of the shortest sequence of rolls so that there's no such subsequence in rolls.
A sequence of rolls of length len is the result of rolling a k sided dice len times.
Example 1:
Input: rolls = [4,2,1,2,3,3,2,4,1], k = 4 Output: 3 Explanation: Every sequence of rolls of length 1, [1], [2], [3], [4], can be taken from rolls. Every sequence of rolls of length 2, [1, 1], [1, 2], ..., [4, 4], can be taken from rolls. The sequence [1, 4, 2] cannot be taken from rolls, so we return 3. Note that there are other sequences that cannot be taken from rolls.
Example 2:
Input: rolls = [1,1,2,2], k = 2 Output: 2 Explanation: Every sequence of rolls of length 1, [1], [2], can be taken from rolls. The sequence [2, 1] cannot be taken from rolls, so we return 2. Note that there are other sequences that cannot be taken from rolls but [2, 1] is the shortest.
Example 3:
Input: rolls = [1,1,3,2,2,2,3,3], k = 4 Output: 1 Explanation: The sequence [4] cannot be taken from rolls, so we return 1. Note that there are other sequences that cannot be taken from rolls but [4] is the shortest.
Constraints:
n == rolls.length1 <= n <= 1051 <= rolls[i] <= k <= 105