java codility training Genomic-range-query

Question

The task is:

A non-empty zero-indexed string S is given. String S consists of N characters from the set of upper-case English letters A, C, G, T.

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Answer 1

Java 100/100

class Solution {
public int[] solution(String S, int[] P, int[] Q) {
    int     qSize       = Q.length;
    int[]   answers     = new int[qSize];

    char[]  sequence    = S.toCharArray();
    int[][] occCount    = new int[3][sequence.length+1];

    int[] geneImpactMap = new int['G'+1];
    geneImpactMap['A'] = 0;
    geneImpactMap['C'] = 1;
    geneImpactMap['G'] = 2;

    if(sequence[0] != 'T') {
        occCount[geneImpactMap[sequence[0]]][0]++;
    }

    for(int i = 0; i < sequence.length; i++) {
        occCount[0][i+1] = occCount[0][i];
        occCount[1][i+1] = occCount[1][i];
        occCount[2][i+1] = occCount[2][i];

        if(sequence[i] != 'T') {
            occCount[geneImpactMap[sequence[i]]][i+1]++;
        }
    }

    for(int j = 0; j < qSize; j++) {
        for(int k = 0; k < 3; k++) {
            if(occCount[k][Q[j]+1] - occCount[k][P[j]] > 0) {
                answers[j] = k+1;
                break;
            }

            answers[j] = 4;
        }            
    }

    return answers;
}
}