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849e65165d
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/**
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* Binary search-based approach to find longest increasing subsequence.
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* Complexity: O(n log n)
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*
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* @param {number[]} sequence
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* @return {number}
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*/
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export default function binarySearchLongestIncreasingSubsequence(sequence) {
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const tails = []; // Array to store the smallest tail elements of increasing subsequences
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// Iterate over the input sequence
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for (let i = 0; i < sequence.length; i++) {
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let left = 0;
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let right = tails.length - 1;
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// Perform binary search to find the largest index `j` where tails[j] <= sequence[i]
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while (left <= right) {
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const mid = Math.floor((left + right) / 2);
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if (tails[mid] <= sequence[i]) {
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left = mid + 1;
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} else {
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right = mid - 1;
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}
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}
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// Update tails[j + 1] to sequence[i]
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if (left === tails.length) {
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tails.push(sequence[i]);
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} else {
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tails[left] = sequence[i];
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}
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}
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// The length of the longest increasing subsequence is the index of the rightmost non-zero element in tails
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return tails.length;
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}
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