GenomicRangeQuery.md

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

The sequence should be returned as:

a Results structure (in C), or a vector of integers (in C++), or a Results record (in Pascal), or an array of integers (in any other programming language). 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.

Assume that:

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. Complexity:

expected worst-case time complexity is O(N+M); expected worst-case space complexity is O(N), beyond input storage (not counting the storage required for input arguments). Elements of input arrays can be modified.

function solution (S, P, Q) {
	var dna = '';
	var ans = [];

	for (var i=0; i < P.length; i++) {
		dna = S.slice(P[i], Q[i] + 1);

		if (dna.indexOf('A') !== -1) {
			ans.push(1)
		} else if (dna.indexOf('C') !== -1) {
			ans.push(2)
		} else if (dna.indexOf('G') !== -1) {
			ans.push(3)
		} else {
			ans.push(4)
		}
	}

	return ans;
}