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

October LeetCoding Challenge 3

Description

Number of Good Pairs

Given an array of integers nums, return the number of good pairs.

A pair (i, j) is called good if nums[i] == nums[j] and i < j.

Example 1:

Input: nums = [1,2,3,1,1,3]
Output: 4
Explanation: There are 4 good pairs (0,3), (0,4), (3,4), (2,5) 0-indexed.

Example 2:

Input: nums = [1,1,1,1]
Output: 6
Explanation: Each pair in the array are good.

Example 3:

Input: nums = [1,2,3]
Output: 0

Constraints:

• 1 <= nums.length <= 100
• 1 <= nums[i] <= 100

Solution

class Solution {
public:
  int numIdenticalPairs(vector<int>& nums) {
    vector<int> count(101);
    int answer = 0;
    for(auto n : nums) {
      answer += count[n];
      count[n] += 1;
    }
    return answer;
  }
};

// Accepted
// 48/48 cases passed (0 ms)
// Your runtime beats 100 % of cpp submissions
// Your memory usage beats 7.1 % of cpp submissions (7.9 MB)