This code beats 99.30% solutions.

I think my code style is not good enough, can somebody help me make my code more elegant?

Thank you!

```
class Solution {
public:
bool containsNearbyDuplicate(vector<int>& nums, int k) {
if (nums.size() == 0) return false;//if empty
size_t i,j;
size_t size = nums.size();
vector<int> cp = nums;//cp = copy of nums
vector<int> duplicates;
sort(cp.begin(), cp.end());//try to find the duplicate ones
for(i = 1; i < size; i++){
if (cp[i - 1] == cp[i])
duplicates.push_back(cp[i]);//record the duplicate ones
}
int little = INT_MAX;
int big = INT_MAX;//initialization
for (i = 0; i < duplicates.size(); i++){//try to find the duplicate element in the nums
for (j = 0; j < size; j++){
if (duplicates[i] == nums[j]){
little = big;
big = j;
if (little != INT_MAX && (big - little) <= k){//only when the two element is close enough
return true;
}
}
}
little = INT_MAX;//reinitialization
big = INT_MAX;
}
return false;
}
};
```