GenomicRangeQuery

Eunseo·2022년 5월 2일

Python3 algorithm codility respectable

Codility

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GenomicRangeQuery 문제 링크
https://app.codility.com/c/run/training6TWF9J-K23/

Summary
개수 세기를 이용한 특정 범위에서 최솟값 찾기

Description

A DNA sequence can be represented as a string consisting of the letters A, C, G and T, which correspond to the types of successive nucleotides in the sequence. Each nucleotide has an impact factor, which is an integer. Nucleotides of types A, C, G and T have impact factors of 1, 2, 3 and 4, respectively. You are going to answer several queries of the form: What is the minimal impact factor of nucleotides contained in a particular part of the given DNA sequence?

The DNA sequence is given as a non-empty string S = S[0]S[1]...S[N-1] consisting of N characters. There are M queries, which are given in non-empty arrays P and Q, each consisting of M integers. The K-th query (0 ≤ K < M) requires you to find the minimal impact factor of nucleotides contained in the DNA sequence between positions P[K] and Q[K].

For example, consider string S = CAGCCTA and arrays P, Q such that:

    P[0] = 2    Q[0] = 4
    P[1] = 5    Q[1] = 5
    P[2] = 0    Q[2] = 6

The answers to these M = 3 queries are as follows:

The part of the DNA between positions 2 and 4 contains nucleotides G and C (twice), whose impact factors are 3 and 2 respectively, so the answer is 2.
The part between positions 5 and 5 contains a single nucleotide T, whose impact factor is 4, so the answer is 4.
The part between positions 0 and 6 (the whole string) contains all nucleotides, in particular nucleotide A whose impact factor is 1, so the answer is 1.

Write a function:

def solution(S, P, Q)

that, given a non-empty string S consisting of N characters and two non-empty arrays P and Q consisting of M integers, returns an array consisting of M integers specifying the consecutive answers to all queries.

Result array should be returned as an array of integers.

For example, given the string S = CAGCCTA and arrays P, Q such that:

    P[0] = 2    Q[0] = 4
    P[1] = 5    Q[1] = 5
    P[2] = 0    Q[2] = 6

the function should return the values [2, 4, 1], as explained above.

Write an efficient algorithm for the following assumptions:

N is an integer within the range [1..100,000];
M is an integer within the range [1..50,000];
each element of arrays P, Q is an integer within the range [0..N − 1];
P[K] ≤ Q[K], where 0 ≤ K < M;
string S consists only of upper-case English letters A, C, G, T.

Checking List

혼자서 문제를 해결

힌트를 보고 해결

답을 보고 해결

My Answer

Total Score : 62%
시간복잡도 : O(N*M)

def solution(S, P, Q):
    dna = {'A':1, 'C':2, 'G':3, 'T':4}
    result = []
    for i in range(len(P)):
        min_val = 5
        for s in S[P[i]:Q[i]+1]:
            min_val = min(min_val, dna[s])
        result.append(min_val)
    return result

Answer Sheet

앞부터 순차적으로 요소의 갯수를 세어 리스트에 저장 후, 원하는 범위에서 요소별 갯수 차를 구하여 0이 아닌 값의 최소 인덱스로 답을 구하는 방식

def solution(S, P, Q):
    dna = {'A':1, 'C':2, 'G':3, 'T':4}
    result = []
    cnt_lis = [[0,0,0,0]]
    counter = [0]*4
    for s in S:
        counter[dna[s]-1] += 1
        cnt_lis.append(counter[:])

    for i in range(len(P)):
        for j in range(4):
            val = cnt_lis[Q[i]+1][j] - cnt_lis[P[i]][j]
            if val != 0:
                result.append(j+1)
                break
    
    return result