68 lines
1.7 KiB
Go
68 lines
1.7 KiB
Go
package main
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import (
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"fmt"
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"math"
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"math/rand"
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"time"
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)
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func main() {
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rand.Seed(time.Now().Unix())
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n := make([]rune, 4)
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for i := range n {
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n[i] = rune(rand.Intn(9) + '1')
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}
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fmt.Printf("Your numbers: %c\n", n)
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fmt.Print("Enter RPN: ")
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var expr string
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fmt.Scan(&expr)
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if len(expr) != 7 {
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fmt.Println("invalid. expression length must be 7." +
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" (4 numbers, 3 operators, no spaces)")
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return
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}
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stack := make([]float64, 0, 4)
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for _, r := range expr {
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if r >= '0' && r <= '9' {
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if len(n) == 0 {
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fmt.Println("too many numbers.")
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return
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}
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i := 0
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for n[i] != r {
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i++
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if i == len(n) {
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fmt.Println("wrong numbers.")
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return
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}
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}
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n = append(n[:i], n[i+1:]...)
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stack = append(stack, float64(r-'0'))
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continue
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}
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if len(stack) < 2 {
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fmt.Println("invalid expression syntax.")
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return
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}
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switch r {
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case '+':
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stack[len(stack)-2] += stack[len(stack)-1]
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case '-':
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stack[len(stack)-2] -= stack[len(stack)-1]
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case '*':
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stack[len(stack)-2] *= stack[len(stack)-1]
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case '/':
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stack[len(stack)-2] /= stack[len(stack)-1]
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default:
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fmt.Printf("%c invalid.\n", r)
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return
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}
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stack = stack[:len(stack)-1]
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}
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if math.Abs(stack[0]-24) > 1e-6 {
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fmt.Println("incorrect.", stack[0], "!= 24")
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} else {
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fmt.Println("correct.")
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}
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}
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