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)
}
//获取num的所有递减数
func getDegressiveNums(num int) []int {
if num < 0 {
return []int{-1}
}
degressiveNums := make([]int, 0)
numStr := strconv.Itoa(num)
length := len(numStr)
//长度为i的子串
for i := 2; i < length; i++ {
//从j开始截取
for j := 0; j < length-i+1; j++ {
//截取数字
n, err := strconv.Atoi(numStr[j : j+i])
checkError(err, "string to integer")
//是否为递减数
if isDegressive(n) {
degressiveNums = append(degressiveNums, n)
}
}
}
return degressiveNums
}
//判断数字num是否是递减数
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)
}
//获取一个slice中最大的数
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
}