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031. Next Permutation.py
52 lines (39 loc) · 1.23 KB
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031. Next Permutation.py
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class Solution(object):
def nextPermutation(self, nums):
"""
# O(n)
# O(1)
:type nums: List[int]
:rtype: void Do not return anything, modify nums in-place instead.
"""
# Use two-pointers: two pointers start from back
# first pointer j stop at descending point
# second pointer i stop at value > nums[j]
# swap and sort rest
# j - position
if not nums:
return nums
j = 0
# find
for i in range(len(nums)-1, -1, -1):
if nums[i-1] < nums[i]:
j = i - 1
break
for i in range(len(nums)-1, -1, -1):
if nums[i] > nums[j]:
nums[i], nums[j] = nums[j], nums[i]
nums[j+1:] = sorted(nums[j+1:])
return
if not nums:
return nums
i = len(nums)
j = 0
for i in range(len(nums)-1,-1,-1):
if nums[i-1] < nums[i]:
j = i-1
break
for i in range(len(nums)-1, -1,-1):
if nums[i] > nums[j]:
nums[i], nums[j] = nums[j], nums[i]
nums[j+1:] = sorted(nums[j+1:])
return