Problem - Candy

Children stand in a line with ratings. Each child gets at least $1$ candy. Children with higher rating than neighbors must get more candies than those neighbors. Minimize total candies.

Example: ratings = [1,0,2]. Child $0$ has rating $1$, child $1$ has rating $0$, child $2$ has rating $2$. Candies: [2,1,2]. Total: $5$.

This needs two passes. One pass cannot satisfy both left and right neighbor constraints simultaneously.