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.

<

Answer 1

In case anyone cares about C:

#include 

struct Results solution(char *S, int P[], int Q[], int M) {    
    int i, a, b, N, *pA, *pC, *pG;
    struct Results result;

    result.A = malloc(sizeof(int) * M);
    result.M = M;

    // calculate prefix sums
    N = strlen(S);
    pA = malloc(sizeof(int) * N);
    pC = malloc(sizeof(int) * N);
    pG = malloc(sizeof(int) * N);
    pA[0] = S[0] == 'A' ? 1 : 0;
    pC[0] = S[0] == 'C' ? 1 : 0;
    pG[0] = S[0] == 'G' ? 1 : 0;
    for (i = 1; i < N; i++) {
        pA[i] = pA[i - 1] + (S[i] == 'A' ? 1 : 0);
        pC[i] = pC[i - 1] + (S[i] == 'C' ? 1 : 0);
        pG[i] = pG[i - 1] + (S[i] == 'G' ? 1 : 0);
    }

    for (i = 0; i < M; i++) {
        a = P[i] - 1;
        b = Q[i];

        if ((pA[b] - pA[a]) > 0) {
            result.A[i] = 1;
        } else if ((pC[b] - pC[a]) > 0) {
            result.A[i] = 2;
        } else if ((pG[b] - pG[a]) > 0) {
            result.A[i] = 3;
        } else {
            result.A[i] = 4;
        }
    }


    return result;
}