最长的正面子阵列

数组A []仅包含'1'和'-1'

构造数组B,其中B [i]是从j开始并在i结束的最长连续子阵列的长度,其中 j < i and A[j] + .. + A[i] > 0

明显的O(n ^ 2)解决方案是:

for (int i = 0; i < A.size(); ++i) {
    j = i-1;
    sum = A[i];
    B[i] = -1; //index which fills criteria not found
    while ( j >=0 ) {
        sum += A[j];
        if (sum > 0)
            B[i] = i - j + 1;
        --j;
    }
}

我正在寻找O(n)解决方案.