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# LeetCode 128. Longest Consecutive Sequence (javascript solution)

### Description:

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.

### Solution:

Time Complexity : O(n)
Space Complexity: O(n)

var longestConsecutive = function(nums) {
// Handle base case of empty array
if (!nums.length) return 0;

// Give ability to look up nums by value
const set = new Set(nums);
let max = 0;

for (const num of set) {
// Make sure we are starting at the beginning of the sequenece
if (set.has(num - 1)) continue;

let currNum = num;
let currMax = 1;

// Look numbers that make a consecutive sequence
while (set.has(currNum + 1)) {
currNum++;
currMax++;
}
// Update max
max = Math.max(max, currMax);
}

return max;
};

Vansh Sharma

Thanks man