public int findPairs(int[] nums, int k) {
if (nums == null || nums.length <= 1 || k < 0) {
int n = nums.length, count = 0;
while (start < n && end < n) {
if (start == end || nums[end] - nums[start] < k) {
else if (nums[end] - nums[start] > k) {
while (start < n && nums[start - 1] == nums[start]) ++start;
end = Math.max(end + 1, start + 1);