코딜리티 - GenomicRangeQuery (javascript)

Task 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] (inclusive).

 

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:

 

function 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.

 

풀이

 

function solution(S, P, Q) {
    const type = ['A', 'C', 'G', 'T'];
    const answer = [];

    for (let i = 0; i < P.length; ++i) {
        const subtype = S.substring(P[i], Q[i] + 1);
        const mintypeIdx = type.findIndex(v => subtype.indexOf(v) != -1);

        answer.push(mintypeIdx + 1);
    }
    
    return answer;
}