Problem analysis of Golang maximum decrement number algorithm

In this paper, the maximum decrement number algorithm of Golang is discussed by example. I will share it with you for your reference as follows:

Given a non-negative integer, find the maximum decrement number contained in the non-negative integer. The declination of a number is the sequence of adjacent digits from large to small.

For example: 95345323, the decreasing number is: 953,95,53,53,532,32, so the maximum decreasing number is 953.

If the input number is negative, return negative 1.

If you can't find the decrement, return negative 1.

Code implementation:

package huawei

import (

    "fmt"

    "sort"

    "strconv"

)

func Test5Base() {

    num := 431492

    degressiveNums := getDegressiveNums(num)

    max := -1

    if len(degressiveNums) > 0 {

        max = getMax(degressiveNums)

    }

    fmt.Println("max:", max)

}

// To obtain num All the decreasing Numbers 

func getDegressiveNums(num int) []int {

    if num < 0 {

        return []int{-1}

    }

    degressiveNums := make([]int, 0)

    numStr := strconv.Itoa(num)

    length := len(numStr)

    // Length of i The substring 

    for i := 2; i < length; i++ {

        // from j Began to intercept 

        for j := 0; j < length-i+1; j++ {

            // Interception of digital 

            n, err := strconv.Atoi(numStr[j : j+i])

            checkError(err, "string to integer")

            // Is a decreasing number 

            if isDegressive(n) {

                degressiveNums = append(degressiveNums, n)

            }

        }

    }

    return degressiveNums

}

// Determine the digital num Is it a decreasing number 

func isDegressive(num int) bool {

    weishu := make([]int, 0)

    for num >= 1 {

        n := num % 10

        weishu = append(weishu, n)

        num /= 10

    }

    return sort.IntsAreSorted(weishu)

}

// To obtain 1 a slice The largest number in 

func getMax(nums []int) int {

    if len(nums) == 0 {

        panic("empty slice.")

    }

    max := nums[0]

    for i := 1; i < len(nums); i++ {

        if nums[i] > max {

            max = nums[i]

        }

    }

    return max

}

I hope this article has been helpful to you in the programming of Go language.