556. 下一个更大元素 III

升序数组查找不是升序的位置

package main
import (
    "fmt"
    "math"
    "sort"
)
func nextGreaterElement(n int) int {
     // 第一步需要拆解成数组
      var nums []int
      for n>0{
            r := n %10
            n = n/10
            nums = append(nums,r)
      }
      idx :=-1
      //[2,3,4,1]
      for i:=0;i<len(nums)-1;i++{
          if nums[i]>nums[i+1] {
                idx = i+1
              break
          }
      }
     if idx==-1 {
        return -1
     }
    //[2,3,4,1]
     for i:=0;i<idx;i++{
          if nums[i]>nums[idx]{
              nums[i],nums[idx] =nums[idx],nums[i]
              break
         }
     }
     // [1,3,4,2]
     sort.Slice(nums[:idx], func(i, j int) bool {
           return  nums[i]>nums[j]
     })
     //[4,3,1,2]
     res :=0
     for i:=len(nums)-1;i>=0;i--{
           res =res*10+nums[i]
         if res>math.MaxInt32 {
             return -1
         }
      }
     return res
}
func main() {
    fmt.Println(nextGreaterElement(1432))
    fmt.Println(nextGreaterElement(1342))
    fmt.Println(nextGreaterElement(123))
    fmt.Println(nextGreaterElement(12))
    fmt.Println(nextGreaterElement(21))
}