https://h30306.github.io/blog/tags/sieve/Recent content in Sieve onHugo -- gohugo.ioenhwork0511@gmail.com (Wei Yi Chung)hwork0511@gmail.com (Wei Yi Chung)© 2026 Wei Yi ChungTue, 20 Oct 2026 00:00:00 +0000https://h30306.github.io/blog/algorithm/number-theory/Tue, 20 Oct 2026 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/algorithm/number-theory/GCD, primality tests, the sieve of Eratosthenes / linear sieve / smallest prime factor (SPF), connecting numbers by prime factors with Union-Find, and splitting an array by the last occurrence of prime factorshttps://h30306.github.io/blog/leetcode/leetcode-2584/Tue, 13 Oct 2026 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/leetcode/leetcode-2584/LeetCode 2584 note: coprime products ⇔ no prime factor in both parts; record each prime’s last index, extend reach left to right, and split after i when reach == ihttps://h30306.github.io/blog/leetcode/leetcode-1998/Mon, 12 Oct 2026 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/leetcode/leetcode-1998/LeetCode 1998 note: numbers in one component can be permuted freely; union each number with its prime factors via SPF, and the array sorts iff each position’s old and new values share a grouphttps://h30306.github.io/blog/leetcode/leetcode-2523/Mon, 12 Oct 2026 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/leetcode/leetcode-2523/LeetCode 2523 note: sieve the primes in range, since only adjacent primes can be closest; or trial-divide rightward from left and stop at the first twin primes with gap 2https://h30306.github.io/blog/leetcode/leetcode-2761/Mon, 12 Oct 2026 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/leetcode/leetcode-2761/LeetCode 2761 note: sieve primes below n, then try x up to n / 2; when x and n - x are both prime, they form a pairhttps://h30306.github.io/blog/leetcode/leetcode-2709/Thu, 07 Aug 2025 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/leetcode/leetcode-2709/LeetCode 2709 note: every pair of indices connects ⇔ one component; factor with SPF and union each number with its prime factors in Union-Find, treating 1 speciallyhttps://h30306.github.io/blog/leetcode/leetcode-3618/Sat, 19 Jul 2025 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/leetcode/leetcode-3618/LeetCode 3618 note: primality is about the index; a sieve of Eratosthenes marks all of 0..n-1 at once, faster than trial division per index