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Given an array of integers and an integer k, find out whether there there are two distinct indices i and j in the array such that nums[i] = nums[j] and the difference between iand j is at most k.
class Solution {
public:
bool containsNearbyDuplicate(vector<int>& nums, int k) {
if(k<0) return false;
if(k>=nums.size()) k=nums.size()-1;
unordered_set<int> s;
for(int i=0;i<nums.size();i++)
{
if(i>k) s.erase(nums[i-k-1]);//限制窗口长度为k。
if(s.find(nums[i])!=s.end()) return true;//找集合s中值为nums[i]的元素的位置，如果没有遍历到最后就找到了，则说明其中有重 //复元素
s.insert(nums[i]);
}
return false;
}
};
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原文地址：http://blog.csdn.net/sinat_24520925/article/details/46628471
