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package LeetCode.array;

import java.util.HashMap;

import java.util.HashSet;

import java.util.Map;

import java.util.Set;

public class LeetCode128 {

public int longestConsecutive(int[] nums) {

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

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

int max = 0;

for(int num : nums){

if (map.containsKey(num)) continue;

Integer leftLn = map.get(num-1);

Integer rightLn = map.get(num+1);

int ln = 1;

if (leftLn != null && rightLn != null) {

ln = leftLn+rightLn+1;

map.replace(num-leftLn, ln);

map.replace(num+rightLn, ln);

map.put(num, ln);

}

else if(leftLn != null) {

ln = leftLn+1;

map.replace(num-leftLn, ln);

map.put(num, ln);

}

else if (rightLn != null){

ln = rightLn+1;

map.replace(num+rightLn, ln);

map.put(num, ln);

}

else {

map.put(num, ln);

}

max = Math.max(max, ln);

}

return max;

}

//=========================

public int longestConsecutive2(int[] nums) {

Set<Integer> set = new HashSet<>();

for (int num : nums){

set.add(num);

}

int max = 0;

for(int num : nums) {

if (!set.remove(num)) continue;

int lt = num-1, rt = num+1;

while (set.remove(lt)) lt--;

while (set.remove(rt)) rt++;

max = Math.max(max, rt-lt-1);

}

return max;

}

}