Locality of reference

main.go

package main

import (
	"fmt"
	"time"
)

func A() {
	start := time.Now()

	var acc int = 0
	var myArr [20000][20000]int

	for col := 0; col < 20000; col++ {
		for row := 0; row < 20000; row++ {
			acc += myArr[row][col]
		}
	}

	end := time.Since(start)

	fmt.Println(end)
	fmt.Println(acc)
}

func B() {
	start := time.Now()

	var acc int
	var myArr [20000][20000]int

	for row := 0; row < 20000; row++ {
		for col := 0; col < 20000; col++ {
			acc += myArr[row][col]
		}
	}

	end := time.Since(start)

	fmt.Println(end)
	fmt.Println(acc)
}

func main() {
	// why???? :)

	A() // 8-9 sec
	B() // 1-2 sec
}