g1501_1600.s1512_number_of_good_pairs.Solution Maven / Gradle / Ivy

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Java-based LeetCode algorithm problem solutions, regularly updated

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package g1501_1600.s1512_number_of_good_pairs;

// #Easy #Array #Hash_Table #Math #Counting #2022_04_09_Time_1_ms_(84.97%)_Space_42.2_MB_(9.05%)

/**
 * 1512 - Number of Good Pairs\.
 *
 * Easy
 *
 * 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`
**/
public class Solution {
    public int numIdenticalPairs(int[] nums) {
        int count = 0;
        for (int i = 0; i < nums.length; i++) {
            for (int j = i + 1; j < nums.length; j++) {
                if (nums[i] == nums[j]) {
                    count++;
                }
            }
        }
        return count;
    }
}