无法获得forf循环来迭代我的程序正常工作的时间

Question

I'm trying to do some exercise our professor gave us to prepare for the exam, but I'm stuck on a pretty annoying problem.
The exercise require two inputs, n and d, and the program has to find the smallest number removing d decimals from the number n. The problem lies around line 40 or 41, because I don't know how to get enough loops to try out every possibily. As for now, the program is limited and won't work properly with most of the inputs.

Example input: 32751960 3
Expected output: 21960 (which is the smallest number we can get by removing 3 decimals from the first number)
What I get: 31960

Thanks in advance to anyone willing to help me.

Code:

package main

import (
    "fmt"
    "os"
    "bufio"
    "strconv"
    "strings"
    "math"
)

var (
    input string
    n, d, max int
    num, dec string
    in []int
)

func main (){
    getInput()
    max = n
    fmt.Println("Variables: ", n, d)

    //Check
    if d>len(num){
        fmt.Println(math.NaN())
        os.Exit(0)
    }

    //The problematic cicle
    for i:=d; i<=len(num); i++{ //On line 40 or 41 lies the problem: I don't get enough loops to check every possible combination,
                                //and at the same time i have to limit the i var to not exceed the slice boundaries
        temp := num[:i-d] + num[i:] 
        if temp == ""{ //To avoid blank strings
            continue
        }
        itemp, _ := strconv.Atoi(temp)
        fmt.Println(itemp)
        if itemp < max {
            max = itemp
        }

    }
    fmt.Println("Best number:",max)
}

func getInput(){
    scanner := bufio.NewScanner(os.Stdin)
    if scanner.Scan(){
        input = scanner.Text()
    }
    for _, s := range strings.Fields(input){
        i, err := strconv.Atoi(s)
        if err != nil {
            fmt.Println(err)
        }
        in = append(in, i) //
    }
    n = in[0] //main number
    d = in[1] //decimals to remove
    num = strconv.Itoa(n)
    dec = strconv.Itoa(d) 
}

Answer 1

You need think about algorithm first.
And the digits to remove do not appear to be contiguous:
Here temp := num[:i-d] + num[i:] you are trying to remove 3 adjacent digits (for d=3) and you should try to remove also not adjacent digits.
Tip:
Remove one digit at a time (k): n = n[:k] + n[k+1:]

---

1. First for learning purpose, I recommend you to try the Brute-force method: Generate all possible states and find the smallest number among them all.

---

1. For smallest number left digit is smaller than right side digit.
   Remove d not contiguous digits then find smallest number. I recommend one loop for d digits:
   for i := 0; i < d; i++ {
   and another loop for finding the k position to remove:
   for j := 0; j < k; j++ {.

Like this and this:

package main

import "fmt"

func main() {
    n := "32751960"
    d := 3
    // fmt.Scan(&n, &d)
    for i := 0; i < d; i++ {
        k := len(n) - 1
        for j := 0; j < k; j++ {
            if n[j] > n[j+1] {
                k = j
                break
            }
        }
        n = n[:k] + n[k+1:]
    }
    fmt.Println(n) // 21960
}

---

1. Using 1 loop, like this:

package main

import "fmt"

func main() {
    n := "322311"
    d := 3
    // fmt.Scan(&n, &d)
    for j := 0; j < len(n)-1; j++ {
        if n[j] > n[j+1] {
            n = n[:j] + n[j+1:]
            j = -1
            d--
            if d <= 0 {
                break
            }
        }
    }
    n = n[:len(n)-d]
    fmt.Println(n) // 211
}