Trapping Rain Waterhard

fn trap(height: Vec<i32>) -> i32 {
    // TODO: two-pointer approach
    0
}

fn main() {
    println!("{}", trap(vec![0,1,0,2,1,0,1,3,2,1,2,1])); // 6
    println!("{}", trap(vec![4,2,0,3,2,5]));               // 9
}