leetcode解题之532. K-diff Pairs in an Array Java版

532. K-diff Pairs in an Array

Given an array of integers and an integer k, you need to find the number of unique k-diff pairs in the array. Here ak-diff pair is defined as an integer pair (i, j), where i and j are both numbers in the array and their absolute difference is k.

Example 1:

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

	public int findPairs1(int[] nums, int k) {
		// k小于0无意义
		if (nums == null || nums.length == 0 || k < 0)
			return 0;
		Map map = new HashMap<>();
		int i = 0;
		for (int num : nums)
			map.put(num, i++);
		int res = 0;
		for (i = 0; i < nums.length; i++)
			// map.get(nums[i] + k) != i避免nums[i] + k也在nums.length之内的情况,
			if (map.containsKey(nums[i] + k) && map.get(nums[i] + k) != i) {
				map.remove(nums[i] + k);
				res++;
			}
		return res;
	}

注意：结果中不能有重复对。