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Abdul Shaik 2024-07-17 10:43:09 +09:00 committed by GitHub
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/**
* Binary search-based approach to find longest increasing subsequence.
* Complexity: O(n log n)
*
* @param {number[]} sequence
* @return {number}
*/
export default function binarySearchLongestIncreasingSubsequence(sequence) {
const tails = []; // Array to store the smallest tail elements of increasing subsequences
// Iterate over the input sequence
for (let i = 0; i < sequence.length; i++) {
let left = 0;
let right = tails.length - 1;
// Perform binary search to find the largest index `j` where tails[j] <= sequence[i]
while (left <= right) {
const mid = Math.floor((left + right) / 2);
if (tails[mid] <= sequence[i]) {
left = mid + 1;
} else {
right = mid - 1;
}
}
// Update tails[j + 1] to sequence[i]
if (left === tails.length) {
tails.push(sequence[i]);
} else {
tails[left] = sequence[i];
}
}
// The length of the longest increasing subsequence is the index of the rightmost non-zero element in tails
return tails.length;
}