用相同的数字集查找下一个更大的数字

给定数字n，请找到与n具有相同数字集且大于n的最小数字。如果n是用其数字集表示的最大可能数，则打印“不可能”。

例子：
为了简化实现，我们将输入数字视为字符串。

Input:  n = "218765"
Output: "251678"

Input:  n = "1234"
Output: "1243"

Input: n = "4321"
Output: "Not Possible"

Input: n = "534976"
Output: "536479"

以下是有关下一个更大数目的一些观察结果。
1)如果所有数字均按降序排列，则输出始终为“不可能”。例如4321。
2)如果所有数字都按升序排序，那么我们需要交换最后两位数字。例如1234。
3)在其他情况下，我们需要从最右边处理数字(为什么?因为我们需要找到所有较大数字中的最小数字)

您现在可以尝试自己开发算法。
以下是用于查找下一个更大数字的算法。
I)从最右边的数字开始遍历给定的数字，继续遍历直到找到一个比先前遍历的数字小的数字。例如，如果输入数字为“ 534976”，由于4小于下一个数字9，我们在4处停止。如果找不到这样的数字，则输出为“不可能”。

II)现在，在上面找到的数字“ d”的右侧搜索大于“ d”的最小数字。对于“ 53 4 976”， 4的右侧包含“ 976”。大于4的最小数字为6 。

III)交换上面找到的两位数，在上面的示例中我们得到53 6 97 4 。

IV)现在，对所有数字进行排序，从“ d”旁边的位置到数字的末尾。排序后得到的数字就是输出。对于上面的例子，我们的排序数字粗体536 974。我们得到“ 536 479 ”，这是输入534976的下一个更大的数字。

以下是上述方法的实现。

C++

// C++ program to find the smallest number which greater than a given number
// and has same set of digits as given number
#include 
#include 
#include 
using namespace std;
 
// Utility function to swap two digits
void swap(char *a, char *b)
{
    char temp = *a;
    *a = *b;
    *b = temp;
}
 
// Given a number as a char array number[], this function finds the
// next greater number.  It modifies the same array to store the result
void findNext(char number[], int n)
{
    int i, j;
 
    // I) Start from the right most digit and find the first digit that is
    // smaller than the digit next to it.
    for (i = n-1; i > 0; i--)
        if (number[i] > number[i-1])
           break;
 
    // If no such digit is found, then all digits are in descending order
    // means there cannot be a greater number with same set of digits
    if (i==0)
    {
        cout << "Next number is not possible";
        return;
    }
 
    // II) Find the smallest digit on right side of (i-1)'th digit that is
    // greater than number[i-1]
    int x = number[i-1], smallest = i;
    for (j = i+1; j < n; j++)
        if (number[j] > x && number[j] < number[smallest])
            smallest = j;
 
    // III) Swap the above found smallest digit with number[i-1]
    swap(&number[smallest], &number[i-1]);
 
    // IV) Sort the digits after (i-1) in ascending order
    sort(number + i, number + n);
 
    cout << "Next number with same set of digits is " << number;
 
    return;
}
 
// Driver program to test above function
int main()
{
    char digits[] = "534976";
    int n = strlen(digits);
    findNext(digits, n);
    return 0;
}

Java

// Java program to find next greater
// number with same set of digits.
import java.util.Arrays;
 
public class nextGreater
{
    // Utility function to swap two digit
    static void swap(char ar[], int i, int j)
    {
        char temp = ar[i];
        ar[i] = ar[j];
        ar[j] = temp;
    }
 
    // Given a number as a char array number[],
    // this function finds the next greater number.
    // It modifies the same array to store the result
    static void findNext(char ar[], int n)
    {
        int i;
         
        // I) Start from the right most digit
        // and find the first digit that is smaller
        // than the digit next to it.
        for (i = n - 1; i > 0; i--)
        {
            if (ar[i] > ar[i - 1]) {
                break;
            }
        }
         
        // If no such digit is found, then all
        // digits are in descending order means
        // there cannot be a greater number with
        // same set of digits
        if (i == 0)
        {
            System.out.println("Not possible");
        }
        else
        {
            int x = ar[i - 1], min = i;
             
            // II) Find the smallest digit on right
            // side of (i-1)'th digit that is greater
            // than number[i-1]
            for (int j = i + 1; j < n; j++)
            {
                if (ar[j] > x && ar[j] < ar[min])
                {
                    min = j;
                }
            }
 
            // III) Swap the above found smallest
            // digit with number[i-1]
            swap(ar, i - 1, min);
 
            // IV) Sort the digits after (i-1)
            // in ascending order
            Arrays.sort(ar, i, n);
            System.out.print("Next number with same" +
                                    " set of digits is ");
            for (i = 0; i < n; i++)
                System.out.print(ar[i]);
        }
    }
 
    public static void main(String[] args)
    {
        char digits[] = { '5','3','4','9','7','6' };
        int n = digits.length;
        findNext(digits, n);
    }
}

Python

# Python program to find the smallest number which
# is greater than a given no. has same set of
# digits as given number
 
# Given number as int array, this function finds the
# greatest number and returns the number as integer
def findNext(number,n):
      
     # Start from the right most digit and find the first
     # digit that is smaller than the digit next to it
     for i in range(n-1,0,-1):
         if number[i] > number[i-1]:
             break
              
     # If no such digit found,then all numbers are in
     # descending order, no greater number is possible
     if i == 1 and number[i] <= number[i-1]:
         print "Next number not possible"
         return
          
     # Find the smallest digit on the right side of
     # (i-1)'th digit that is greater than number[i-1]
     x = number[i-1]
     smallest = i
     for j in range(i+1,n):
         if number[j] > x and number[j] < number[smallest]:
             smallest = j
          
     # Swapping the above found smallest digit with (i-1)'th
     number[smallest],number[i-1] = number[i-1], number[smallest]
      
     # X is the final number, in integer datatype
     x = 0
     # Converting list upto i-1 into number
     for j in range(i):
         x = x * 10 + number[j]
      
     # Sort the digits after i-1 in ascending order
     number = sorted(number[i:])
     # converting the remaining sorted digits into number
     for j in range(n-i):
         x = x * 10 + number[j]
      
     print "Next number with set of digits is",x
 
 
# Driver Program to test above function
digits = "534976"        
 
# converting into integer array,
# number becomes [5,3,4,9,7,6]
number = map(int ,digits)
findNext(number, len(digits))
 
# This code is contributed by Harshit Agrawal

C#

// C# program to find next greater
// number with same set of digits.
using System;
                     
public class nextGreater
{
    // Utility function to swap two digit
    static void swap(char []ar, int i, int j)
    {
        char temp = ar[i];
        ar[i] = ar[j];
        ar[j] = temp;
    }
 
    // Given a number as a char array number[],
    // this function finds the next greater number.
    // It modifies the same array to store the result
    static void findNext(char []ar, int n)
    {
        int i;
         
        // I) Start from the right most digit
        // and find the first digit that is smaller
        // than the digit next to it.
        for (i = n - 1; i > 0; i--)
        {
            if (ar[i] > ar[i - 1])
            {
                break;
            }
        }
         
        // If no such digit is found, then all
        // digits are in descending order means
        // there cannot be a greater number with
        // same set of digits
        if (i == 0)
        {
            Console.WriteLine("Not possible");
        }
        else
        {
            int x = ar[i - 1], min = i;
             
            // II) Find the smallest digit on right
            // side of (i-1)'th digit that is greater
            // than number[i-1]
            for (int j = i + 1; j < n; j++)
            {
                if (ar[j] > x && ar[j] < ar[min])
                {
                    min = j;
                }
            }
 
            // III) Swap the above found smallest
            // digit with number[i-1]
            swap(ar, i - 1, min);
 
            // IV) Sort the digits after (i-1)
            // in ascending order
            Array.Sort(ar, i, n-i);
            Console.Write("Next number with same" +
                                    " set of digits is ");
            for (i = 0; i < n; i++)
                Console.Write(ar[i]);
        }
    }
 
    // Driver code
    public static void Main(String[] args)
    {
        char []digits = { '5','3','4','9','7','6' };
        int n = digits.Length;
        findNext(digits, n);
    }
}
 
// This code is contributed by 29AjayKumar

Javascript

 
// JavaScript program to find the
// smallest number which is greater
// than a given no. has same set of
// digits as given number
 
// Given number as int array, this
// function finds the greatest number
// and returns the number as integer
function findNext(number, n)
{
     
    // Start from the right most digit
    // and find the first digit that is
    // smaller than the digit next to it
    for(var i = n - 1; i >= 0; i--)
    {
        if (number[i] > number[i - 1])
            break;
    }
     
    // If no such digit found,then all
    // numbers are in descending order,
    // no greater number is possible
    if (i == 1 && number[i] <= number[i - 1])
    {
        document.write("Next number not possible");
        return;
    }  
     
    // Find the smallest digit on the
    // right side of (i-1)'th digit
    // that is greater than number[i-1]
    let x = number[i - 1];
    let smallest = i;
     
    for(let j = i + 1; j < n; j++)
    {
        if (number[j] > x &&
            number[j] < number[smallest])
        smallest = j;
    }
     
    // Swapping the above found smallest
    // digit with (i-1)'th
    let temp = number[smallest];
    number[smallest] = number[i - 1];
    number[i - 1] = temp;
     
    // X is the final number, in integer datatype
    x = 0
     
    // Converting list upto i-1 into number
    for(let j = 0; j < i; j++)
        x = x * 10 + number[j];
     
    // Sort the digits after i-1 in ascending order
    number = number.slice(i, number.length + 1);
    number.sort()
     
    // Converting the remaining sorted
    // digits into number
    for(let j = 0; j < n - i; j++)
        x = x * 10 + number[j];
     
    document.write("Next number with " +
                   "set of digits is " + x);
}
 
// Driver code
let digits = "534976"      
 
// Converting into integer array,
// number becomes [5,3,4,9,7,6]
let number = []
for(let i = 0; i < digits.length; i++)
    number[i] = Number(digits[i]);
 
findNext(number, digits.length);
 
// This code is contributed by rohan07
 

输出：

Next number with same set of digits is 536479