LeetCode 886 Possible Bipartition - Index Handling

People are numbered $1$ to $n$, not $0$ to $n-1$. You have two options: create arrays of size $n+1$ and use indices $1$ to $n$ (index $0$ stays unused), or subtract $1$ from all person numbers to make them $0$-indexed, then use arrays of size $n$.

Both work. The first is simpler to think about. Remember your loop bounds: iterate from $1$ to $n$, not $0$ to $n-1$. Off-by-one errors are common here.