Given a N x M matrix, you are asked to find the minimum cost path from the top to the bottom. You can start at any column in the first row. If you are at point (i,j), you are constrained to move to only (i+1, j), (i+1, j-1), (i+1,j+1) in the next row.

This is a simple DP question, but I am wondering which question on leetcode this is? I'm pretty certain I've seen it before, but I can't find it.