Next Permutation.py

[DevilANANDGupta]

class Solution(object):
def nextPermutation(self, nums):
"""
:type nums: List[int]
:rtype: void Do not return anything, modify nums in-place instead.
"""

    i = j = len(nums)-1
    while i > 0 and nums[i]<=nums[i-1]:
        i-=1
    i-=1
    if i<0:
        nums.reverse()
        return
    
    while j>i and nums[j]<=nums[i]:
        j-=1
    
    nums[i],nums[j] = nums[j], nums[i]
    
    k,l = i+1, len(nums)-1
    
    while k<l:
        nums[k],nums[l] = nums[l], nums[k]
        k+=1
        l-=1