In this post, we are going to solve the Longest Consecutive Sequence Leetcode Solution problem of Leetcode. This Leetcode problem is done in many programming languages like C++, Java, and Python.
Problem
Given an unsorted array of integers nums, return the length of the longest consecutive elements sequence.
You must write an algorithm that runs in O(n) time.
Example 1:
Input: nums = [100,4,200,1,3,2]
Output: 4
Explanation: The longest consecutive elements sequence is [1, 2, 3, 4]. Therefore its length is 4.
Example 2:
Input: nums = [0,3,7,2,5,8,4,6,0,1] Output: 9
Constraints:
0 <= nums.length <= 105-109 <= nums[i] <= 109
Now, let’s see the leetcode solution of Longest Consecutive Sequence Leetcode Solution.
Longest Consecutive Sequence Leetcode Solution in Python
class Solution:
def longestConsecutive(self, nums: List[int]) -> int:
ans = 0
seen = set(nums)
for num in nums:
if num - 1 in seen:
continue
length = 0
while num in seen:
num += 1
length += 1
ans = max(ans, length)
return ansLongest Consecutive Sequence Leetcode Solution in CPP
class Solution {
public:
int longestConsecutive(vector<int>& nums) {
int ans = 0;
unordered_set<int> seen{begin(nums), end(nums)};
for (int num : nums) {
// Num is the start of a sequence
if (seen.count(num - 1))
continue;
int length = 1;
while (seen.count(++num))
++length;
ans = max(ans, length);
}
return ans;
}
};Longest Consecutive Sequence Leetcode Solution in Java
class Solution {
public int longestConsecutive(int[] nums) {
int ans = 0;
Set<Integer> seen = Arrays.stream(nums).boxed().collect(Collectors.toSet());
for (int num : nums) {
// Num is the start of a sequence
if (seen.contains(num - 1))
continue;
int length = 1;
while (seen.contains(++num))
++length;
ans = Math.max(ans, length);
}
return ans;
}
}Note: This problem Longest Consecutive Sequence is generated by Leetcode but the solution is provided by Chase2learn This tutorial is only for Educational and Learning purpose.
