Advent of Code 2021 Day 9

9a.go

package main

import (
	_ "embed"
	"fmt"
	"strconv"
	"strings"
)

//go:embed input.txt
var input string

func main() {
	lines := strings.Split(input, "\n")
	grid := make([][]int, len(lines))
	for i, line := range lines {
		grid[i] = make([]int, len(line))
		for j, num := range line {
			num, err := strconv.Atoi(string(num))
			if err != nil {
				panic(err)
			}
			grid[i][j] = num
		}
	}

	// Find risk points
	risk := 0
	for r, row := range grid {
		for c, val := range row {
			// Go through neighbors
			isLower := true
			for roff := -1; roff <= 1; roff++ {
				for coff := -1; coff <= 1; coff++ {
					if !isLower {
						continue
					}
					if !(roff == 0 && coff == 0) && (roff == 0 || coff == 0) {
						// Check offset
						lessZero := (c+coff < 0) || (r+roff < 0)
						greaterZero := (c+coff >= len(row)) || (r+roff >= len(grid))
						if !lessZero && !greaterZero {
							if grid[r+roff][c+coff] <= val {
								isLower = false
							}
						}
					}
				}
			}

			// Add risk
			if isLower {
				risk += val + 1
			}
		}
	}

	fmt.Println(risk)
}

9b.txt

Can't figure out how to solve :(