[leetcode] 1409. Queries on a Permutation With Key

    科技2024-04-15  97

    Description

    Given the array queries of positive integers between 1 and m, you have to process all queries[i] (from i=0 to i=queries.length-1) according to the following rules:

    In the beginning, you have the permutation P=[1,2,3,…,m].For the current i, find the position of queries[i] in the permutation P (indexing from 0) and then move this at the beginning of the permutation P. Notice that the position of queries[i] in P is the result for queries[i].

    Return an array containing the result for the given queries.

    Example 1:

    Input: queries = [3,1,2,1], m = 5 Output: [2,1,2,1] Explanation: The queries are processed as follow: For i=0: queries[i]=3, P=[1,2,3,4,5], position of 3 in P is 2, then we move 3 to the beginning of P resulting in P=[3,1,2,4,5]. For i=1: queries[i]=1, P=[3,1,2,4,5], position of 1 in P is 1, then we move 1 to the beginning of P resulting in P=[1,3,2,4,5]. For i=2: queries[i]=2, P=[1,3,2,4,5], position of 2 in P is 2, then we move 2 to the beginning of P resulting in P=[2,1,3,4,5]. For i=3: queries[i]=1, P=[2,1,3,4,5], position of 1 in P is 1, then we move 1 to the beginning of P resulting in P=[1,2,3,4,5]. Therefore, the array containing the result is [2,1,2,1].

    Example 2:

    Input: queries = [4,1,2,2], m = 4 Output: [3,1,2,0]

    Example 3:

    Input: queries = [7,5,5,8,3], m = 8 Output: [6,5,0,7,5]

    Constraints:

    1 <= m <= 10^31 <= queries.length <= m1 <= queries[i] <= m

    分析

    题目的意思是:给你queries,代表着排列中的数,返回其对应的数字,在每次query后,需要把当前位置的数字放到最开始的位置,然后其他位置的数依次移动到后面。 所以我的思路也很直接,先把这个排列表示出来,用P表示,按照query的顺序每次排列P,即把找到的数提前,其他的移动到后面去。

    代码

    class Solution: def processQueries(self, queries: List[int], m: int) -> List[int]: P=[i+1 for i in range(m)] res=[] for query in queries: idx=P.index(query) res.append(idx) pos=idx while(pos>0): P[pos]=P[pos-1] pos-=1 P[0]=query return res
    Processed: 0.017, SQL: 8