Go
Part 2: Read the whole input in a rune matrix. Scan it column by column, store the numbers as you go, ignoring all spaces, and store the operand when you find it. When you hit an empty column or the end, do the operation and add it to the total.
spoiler
func part2() {
// file, _ := os.Open("sample.txt")
file, _ := os.Open("input.txt")
defer file.Close()
scanner := bufio.NewScanner(file)
chars := [][]rune{}
for scanner.Scan() {
chars = append(chars, []rune(scanner.Text()))
}
m := len(chars)
n := len(chars[0])
var op rune
nums := []int{}
total := 0
for j := range n {
current := []rune{}
for i := range m {
if chars[i][j] == '+' || chars[i][j] == '*' {
op = chars[i][j]
} else if chars[i][j] != ' ' {
current = append(current, chars[i][j])
}
}
if len(current) > 0 {
x, _ := strconv.Atoi(string(current))
nums = append(nums, x)
}
if len(current) == 0 || j == n-1 {
result := 0
if op == '*' {
result = 1
}
for _, x := range nums {
if op == '+' {
result = result + x
} else {
result = result * x
}
}
total += result
nums = []int{}
}
}
fmt.Println(total)
}