1. (4 points) la) Use pseudocode to specify a brute-force algorithm that determines when given as input a sequence of n positive integers whether there are two distinct terms of the sequence that have as sum a third term. The algorithm should loop through all triples of terms of the sequence, checking whether the sum of the first two terms equals the third. lb) Give a big-O estimate for the complexity of the brute-force algorithm from part (a). 1c) Devise a more efficient algorithm for solving the problem that first sorts the input sequence and then checks for each pair of terms whether their difference is in the sequence. 1d) Give a big-O estimate for the complexity of this algorithm. Is it more efficient than the brute-force algorithm