1512. Number of Good Pairs

Given an array of integers nums.

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

Return the number of good pairs.

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

---

直接按题意做就行：

class Solution {
public:
	int numIdenticalPairs(vector<int>& nums) {
		int ans = 0, n = nums.size();
		for (int i = 0; i < n; ++i) {
			for (int j = i + 1; j < n; ++j) {
				if (nums[i] == nums[j])++ans;
			}
		}
		return ans;
	}
};

本代码提交AC，用时8MS。