219.cpp

// hash-33ms.cpp
class Solution {
public:
  bool containsNearbyDuplicate(vector<int> &nums, int k) {
    unordered_map<int, int> map;
    int len = nums.size();
    for (int i = 0; i < len; ++i)
      if (map.find(nums[i]) != map.end()) {
        if (abs(i - map[nums[i]]) <= k)
          return 1;
        map[nums[i]] = i;
      } else
        map[nums[i]] = i;
    return 0;
  }
};