package main

import (
    "fmt"
    "time"
)

func Sum(values []interface{}) int {
    var total int
    for _, v := range values {
        total += v.(int) // การแปลงประเภททำให้ช้าลง
    }
    return total
}

func main() {
    values := make([]interface{}, 1000000)
    for i := 0; i < 1000000; i++ {
        values[i] = i
    }

    start := time.Now()
    fmt.Println("Sum:", Sum(values)) // เกิด panic ได้ถ้าไม่ใช่ int
    fmt.Println("Duration:", time.Since(start))
}

package main

import "fmt"

// T คือ Type Parameter ที่รองรับ int และ float64
func Sum[T int | float64](nums []T) T {
    var total T
    for _, num := range nums {
        total += num
    }
    return total
}

func main() {
    fmt.Println(Sum([]int{1, 2, 3}))       // 6
    fmt.Println(Sum([]float64{1.5, 2.5})) // 4.0
}

package main

import "fmt"

type Box[T any] struct {
    Value T
}

func main() {
    intBox := Box[int]{Value: 100}
    strBox := Box[string]{Value: "Hello"}

    fmt.Println(intBox.Value) // 100
    fmt.Println(strBox.Value) // Hello
}

package main

import "fmt"

type Ordered interface {
    int | float64 | string
}

func Max[T Ordered](a, b T) T {
    if a > b {
        return a
    }
    return b
}

func main() {
    fmt.Println(Max(5, 10))         // 10
    fmt.Println(Max(3.5, 2.8))     // 3.5
    fmt.Println(Max("Go", "Golang")) // Golang
}

package main

import "fmt"

type Stack[T any] struct {
    items []T
}

func (s *Stack[T]) Push(item T) {
    s.items = append(s.items, item)
}

func (s *Stack[T]) Pop() (T, bool) {
    if len(s.items) == 0 {
        var zero T
        return zero, false
    }
    item := s.items[len(s.items)-1]
    s.items = s.items[:len(s.items)-1]
    return item, true
}

func main() {
    intStack := Stack[int]{}
    intStack.Push(10)
    intStack.Push(20)

    val, ok := intStack.Pop()
    if ok {
        fmt.Println(val) // 20
    }

    strStack := Stack[string]{}
    strStack.Push("Go")

    valStr, ok := strStack.Pop()
    if ok {
        fmt.Println(valStr) // Go
    }
}