2022-02-09 Daily-Challenge

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Today I have done leetcode's February LeetCoding Challenge with cpp.

February LeetCoding Challenge 9

Description

K-diff Pairs in an Array

Given an array of integers nums and an integer k, return the number of unique k-diff pairs in the array.

A k-diff pair is an integer pair (nums[i], nums[j]), where the following are true:

  • 0 <= i < j < nums.length
  • |nums[i] - nums[j]| == k

Notice that |val| denotes the absolute value of val.

Example 1:

Input: nums = [3,1,4,1,5], k = 2
Output: 2
Explanation: There are two 2-diff pairs in the array, (1, 3) and (3, 5).
Although we have two 1s in the input, we should only return the number of unique pairs.

Example 2:

Input: nums = [1,2,3,4,5], k = 1
Output: 4
Explanation: There are four 1-diff pairs in the array, (1, 2), (2, 3), (3, 4) and (4, 5).

Example 3:

Input: nums = [1,3,1,5,4], k = 0
Output: 1
Explanation: There is one 0-diff pair in the array, (1, 1).

Constraints:

  • 1 <= nums.length <= 104
  • -107 <= nums[i] <= 107
  • 0 <= k <= 107

Solution

class Solution {
public:
  int findPairs(vector<int>& nums, int k) {
    unordered_map<int, int> cnt;
    for(auto i : nums) {
      cnt[i] += 1;
    }

    int answer = 0;
    for(auto [i, c] : cnt) {
      if(k) answer += cnt.count(i + k);
      else answer += c > 1;
    }
    return answer;
  }
};

// Accepted
// 60/60 cases passed (11 ms)Vubmissions
// Your memory usage beats 68.98 % of cpp submissions (13.1 MB)
Algorithm