public int findLHS(int[] nums) {

if (nums == null || nums.length == 0) return 0;

int res = 0;

Map<Integer, Integer> map = new HashMap<>();

for (int n: nums) {

map.put(n, map.getOrDefault(n, 0)+1);

int b = map.get(n);

if (map.containsKey(n-1)) {

int a = map.get(n-1);

if (a + b > res) res = a + b;

}

if (map.containsKey(n+1)) {

int a = map.get(n+1);

if (a + b > res) res = a + b;

}

}

return res;

}

/**

public int findLHS2(int[] nums) {

HashMap < Integer, Integer > map = new HashMap < > ();

int res = 0;

for (int num: nums) {

map.put(num, map.getOrDefault(num, 0) + 1);

}

for (int key: map.keySet()) {

if (map.containsKey(key + 1))

res = Math.max(res, map.get(key) + map.get(key + 1));

}

return res;

}

/**

public int findLHS3(int[] nums) {

Arrays.sort(nums);

int prev_count = 1, res = 0;

for (int i = 0; i < nums.length; i++) {

int count = 1;

if (i > 0 && nums[i] - nums[i - 1] == 1) {

while (i < nums.length - 1 && nums[i] == nums[i + 1]) {

count++;

i++;

}

res = Math.max(res, count + prev_count);

prev_count = count;

} else {

while (i < nums.length - 1 && nums[i] == nums[i + 1]) {

count++;

i++;

}

prev_count = count;

}

}

return res;

}

public int findLHS4(int[] nums) {

if (nums == null || nums.length == 0) return 0;

Arrays.sort(nums);

int N = nums.length;

int res = 0;

int preCount = -1;

int pre = 0;

int count = 1;

int curr = nums[0];

int i = 1;

while (i < N && nums[i] == curr) {

count++;

i++;

}

while (i < N) {

if (nums[i] == curr) {

count++;

} else {

if (preCount != -1 && curr == pre + 1 && (count + preCount) > res) {

res = count + preCount;

}

preCount = count;

pre = curr;

count = 1;

curr = nums[i];

}

i++;

}

if (preCount != -1 && curr == pre + 1 && (count + preCount) > res) {

res = count + preCount;

}

return res;

}