Next_Permutation.py

def nextPermutation(array):
        """
        Function for next Permutation
        It rearranges numbers into the lexicographically next greater permutation of numbers.
        If such an arrangement is not possible, it will rearrange it as the lowest possible order (i.e., sorted in ascending order).
        """
        length = len(array)
        if length <= 2:
            return array.reverse()
        pointer = length - 2
        
        while pointer >= 0 and array[pointer] >= array[pointer + 1]:
            pointer -= 1
        
        if pointer == -1:
            return array.reverse()
        
        for number in range(length - 1, pointer, -1):
            if array[pointer] < array[number]:
                array[pointer], array[number] = array[number], array[pointer]
                break
        
        array[pointer + 1:] = reversed(array[pointer + 1:])
        return array


if __name__ == "__main__":
    #User input for both the strings
    print('Enter values of the array')
    array = list(map(int, input().rstrip().split()))
    print(nextPermutation(array))
        
"""
Input: numbers = [1,1,5]
Output: [1,5,1]
Input: numbers = [3,2,1]
Output: [1,2,3]
"""