Problem #11

Problem link
Solution:

package main

import (
    "strconv"
    "io/ioutil"
    "strings"
)

func main() {
    fileBuf, err := ioutil.ReadFile("011_input.txt")
    if err != nil {
        panic(err.String())
    }
    fileStr := string(fileBuf)
    lines := strings.Split(fileStr, "\n", 20)
    arr := make([][]uint, 20)
    var strArr []string
    for i := range lines {
        arr[i] = make([]uint, 20)
        strArr = strings.Split(lines[i], " ", 20)
        for j := range arr[i] {
            intvalue, _ := strconv.Atoi(strArr[j])
            arr[i][j] = uint(intvalue)
        }
    }
    max := uint(0)
    //left to right
    for i := range arr {
        for j := 0; j < 17; j++ {
            mul := arr[i][j] * arr[i][j+1] * arr[i][j+2] * arr[i][j+3]
            if mul > max {
                max = mul
            }
        }
    }
    //up to down
    for i := 0; i < 17; i++ {
        for j := range arr[i] {
            mul := arr[i][j] * arr[i+1][j] * arr[i+2][j] * arr[i+3][j]
            if mul > max {
                max = mul
            }
        }
    }
    //first diagonal
    for i := 0; i < 17; i++ {
        for j := 0; j < 17; j++ {
            mul := arr[i][j] * arr[i+1][j+1] * arr[i+2][j+2] * arr[i+3][j+3]
            if mul > max {
                max = mul
            }
        }
    }
    //second diagonal
    for i := 3; i < 20; i++ {
        for j := 0; j < 17; j++ {
            mul := arr[i][j] * arr[i-1][j+1] * arr[i-2][j+2] * arr[i-3][j+3]
            if mul > max {
                max = mul
            }
        }
    }
    println(max)
}

Input file is renamed as 011_input.txt.

Result: 70600674
Time: 0m0.005s