Leetcode 2086. Minimum Number of Food Buckets to Feed the Hamsters

Place the minimum number of buckets on '.' positions in a 1D string so that every 'H' has a bucket at index i-1 or i+1, or return -1 if some hamster has no adjacent empty spot. This is a linear greedy/covering problem on a path (detecting impossible configurations like an H with both neighbors being H or out of bounds).