Leetcode Two sum problem

1. Two Sum Working: seen keeps track of numbers we’ve already visited and their indices. For each num, we calculate complement = target-num. If the complement is already in seen, we return the pair of indices. Otherwise, we store the current number with its index. 167. Two Sum II - Input Array Is Sorted Working: Start with two pointers left at the beginning, right at the end. Compute the sum of the two numbers. If the sum equals the target, return their indices. - If the sum is too small, move left forward to increase the sum. If the sum is too large, move right backward to decrease the sum.