Trapping Rain Waterhard

package main

import "fmt"

func trap(height []int) int {
	// TODO: two-pointer approach — track maxLeft, maxRight
	return 0
}

func main() {
	fmt.Println(trap([]int{0,1,0,2,1,0,1,3,2,1,2,1})) // 6
	fmt.Println(trap([]int{4,2,0,3,2,5}))               // 9
}