day8.go

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func isVisible(x int, y int, t [][]int) bool {
	// given an x/y coordinate, it will build a slice of integers
	// containing the values going straight up, straight down,
	// left and right. Then it will determine the tree's visibility.
	// NOTE: y is resolved FIRST! so t[y][x]

	var up, down, left, right []int

	// quick wins
	if x == 0 || x == len(t[y])-1 {
		return true
	}
	if y == 0 || y == len(t)-1 {
		return true
	}

	// otherwise, build the slices.
	// all the ones above
	for i := y - 1; i >= 0; i-- {
		up = append(up, t[i][x])
	}
	// all below
	for i := y + 1; i < len(t); i++ {
		down = append(down, t[i][x])
	}
	// all to the left
	for i := x - 1; i >= 0; i-- {
		left = append(left, t[y][i])
	}
	// all to the right
	for i := x + 1; i < len(t[y]); i++ {
		right = append(right, t[y][i])
	}

	num := t[y][x] // for simplicity's sake

	dirArray := [4]*[]int{&up, &down, &left, &right}

	for _, v := range dirArray {
		visibleDirection := true
		for _, w := range *v {
			if num <= w {
				visibleDirection = false
				break
			}
		}
		if visibleDirection {
			return true
		}
	}
	return false
}

func main() {
	readFile, err := os.Open("input")

	if err != nil {
		fmt.Println(err)
	}

	defer readFile.Close()

	fileScanner := bufio.NewScanner(readFile)
	fileScanner.Split(bufio.ScanLines)

	trees := make([][]int, 0)

	for fileScanner.Scan() {
		line := fileScanner.Text()
		temp := make([]int, 0)
		for _, ch := range line {
			num, err := strconv.Atoi(fmt.Sprintf("%c", ch))
			if err != nil {
				fmt.Println("Could not convert!", err)
			}
			temp = append(temp, num)
		}
		trees = append(trees, temp)
	}
	// fmt.Printf("Contents of trees: +%v\n", trees)

	// Now loop through every single number, providing x and y coords
	// fmt.Println("Is 2/2 visible?", isVisible(2, 2, trees))
	var counter int = 0
	for i, v := range trees { // y
		for j, _ := range v { // x
			if isVisible(j, i, trees) {
				counter++
			}
		}
	}
	fmt.Println("Amount of trees visible:", counter)
}