Leetcode: the shortest dice sequence impossible to get [thinking questions + grouping ideas]

analysis

A group of 1-k Can create a length
use set See how many groups you can save 1-k
Then the answer is how many groups + 1

ac code

class Solution:
    def shortestSequence(self, rolls: List[int], k: int) -> int:
        #  Thinking questions , A group of 1-k Make a length 
        s = set()
        ans = 0
        for num in rolls:
            s.add(num)
            if len(s) == k:
                s.clear()
                ans += 1
        
        return ans + 1

summary

Thinking first
The idea of grouping and blocking