Longest Consecutive Sequence
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.
function longestConsecutive(nums) {
if (nums == null || nums.length === 0) return 0;
const set = new Set(nums);
let max = 0;
for (let num of set) {
if (set.has(num - 1)) continue; // make sure starting from the beginning of sequence
let currNum = num;
let currMax = 1;
while (set.has(currNum + 1)) {
currNum++;
currMax++;
}
max = Math.max(max, currMax);
}
return max;
}Related Problems
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You must solve the problem without modifying the array nums and uses only constant extra space.
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Please solve it without using the built-in JSON.stringify method.
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