1512. Number of Good Pairs

Link: https://leetcode.com/problems/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

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題目翻譯:

keyword nums[i] == nums[j] and i < j

程式思路:

很 easy 的題目，nums[i] == nums[j] and i < j 照這個條件做就好。

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