Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and the absolute difference between i and j is at most k.
Example 1:
Input: nums = [1,2,3,1], k = 3
Output: true
Example 2:
Input: nums = [1,0,1,1], k = 1
Output: true
Example 3:
Input: nums = [1,2,3,1,2,3], k = 2
Output: false
解题要点：
保持一个k长度的set，检测里面是否有重复数。
class Solution(object):
def containsNearbyDuplicate(self, nums, k):
"""
:type nums: List[int]
:type k: int
:rtype: bool
"""
s = set()
for i in range(len(nums)):
if nums[i] in s:
return True
s.add(nums[i])
if(len(s) > k):
s.remove(nums[i - k])
return False
直接用dict记录index和value，然后检测差值是否在k值内。
class Solution(object):
def containsNearbyDuplicate(self, nums, k):
"""
:type nums: List[int]
:type k: int
:rtype: bool
"""
mydict = dict()
for i, v in enumerate(nums):
if v in mydict and i - mydict[v] <= k:
return True
mydict[v] = i
return False