Comparing Performance of Ruby and Golang With a Benchmark

package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"os"
)

var grid [][]int
var gridDim [2]int
var a = make(map[[2]int]bool)

func main() {
	jsonFile, err := ioutil.ReadFile(os.Args[1])
	if err != nil {
		fmt.Println(err)
	}
	json.Unmarshal([]byte(jsonFile), &grid)
	gridDim[0] = len(grid)
	gridDim[1] = len(grid[0])

	greatest := 0
	for rowIndex, row := range grid {
		for colIndex := range row {
			currentKey := [2]int{rowIndex, colIndex}
			_, hasKey := a[currentKey]
			if hasKey {
				continue
			}
			a[currentKey] = true
			total := findCluster(currentKey, true)
			if total > greatest {
				greatest = total
			}
		}
	}
	fmt.Println(greatest)
}

func getValFromGrid(coords [2]int) int {
	return grid[coords[0]][coords[1]]
}

func findCluster(coords [2]int, first bool) int {
	currentValue := getValFromGrid(coords)
	adjascentSquares := [4][2]int{
		{coords[0] - 1, coords[1]},
		{coords[0], coords[1] - 1},
		{coords[0] + 1, coords[1]},
		{coords[0], coords[1] + 1},
	}
	total := 1
	for _, v := range adjascentSquares {
		_, hasKey := a[v]
		if hasKey {
			continue
		}
		if withinGrid(v) && hasSameValue(currentValue, v) {
			a[v] = true
			total = total + findCluster(v, false)
		}
	}
	return total
}

func hasSameValue(val int, coords [2]int) bool {
	return getValFromGrid(coords) == val
}

func withinGrid(coords [2]int) bool {
	return coords[0] >= 0 &&
		coords[0] < gridDim[0] &&
		coords[1] >= 0 &&
		coords[1] < gridDim[1]
}