https://h30306.github.io/blog/tags/enumeration/Recent content in Enumeration onHugo -- gohugo.ioenhwork0511@gmail.com (Wei Yi Chung)hwork0511@gmail.com (Wei Yi Chung)© 2026 Wei Yi ChungWed, 21 Oct 2026 00:00:00 +0000https://h30306.github.io/blog/algorithm/array/Wed, 21 Oct 2026 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/algorithm/array/Adjacent comparisons and walking monotonic runs (uphill, downhill, hills and valleys), keeping prefix / suffix maximums and sums in one pass, enumerating pairs in small ranges, and breaking ties with tuple keyshttps://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-3548/Mon, 27 Jul 2026 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/leetcode/leetcode-3548/LeetCode 3548 note: try each horizontal cut (transpose for vertical); the difference must equal a cell on the larger side, and a one-row or one-column side can only drop an end cell, while any cell works otherwisehttps://h30306.github.io/blog/leetcode/leetcode-3984/Mon, 06 Jul 2026 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/leetcode/leetcode-3984/LeetCode 3984 note: replacing a composite k by one of its prime factors only helps (more values divisible, smaller k), so try every prime factor of the numbers plus 2, running Kadane once per candidatehttps://h30306.github.io/blog/leetcode/leetcode-1878/Tue, 23 Jun 2026 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/leetcode/leetcode-1878/LeetCode 1878 note: enumerate every top vertex and size, walk the four edges, and keep the three largest distinct sumshttps://h30306.github.io/blog/leetcode/leetcode-3713/Mon, 22 Jun 2026 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/leetcode/leetcode-3713/LeetCode 3713 note: fix the start and extend right; “every character has the same count” means “highest count × kinds = length”, an O(1) check per stephttps://h30306.github.io/blog/leetcode/leetcode-3910/Sun, 26 Apr 2026 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/leetcode/leetcode-3910/LeetCode 3910 note: n is tiny, so enumerate subsets with a bitmask, check the even sum first, then check that the induced subgraph is connectedhttps://h30306.github.io/blog/leetcode/leetcode-3833/Sun, 08 Feb 2026 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/leetcode/leetcode-3833/LeetCode 3833 note: keep a suffix sum from the right and compare nums[i] × count > sum on the right, with no floats and without counting itselfhttps://h30306.github.io/blog/leetcode/leetcode-3827/Sun, 01 Feb 2026 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/leetcode/leetcode-3827/LeetCode 3827 note: the only numbers with all-equal bits are 0 and 2^k - 1, so the count is (n + 1).bit_length()https://h30306.github.io/blog/leetcode/leetcode-2122/Mon, 26 Jan 2026 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/leetcode/leetcode-2122/LeetCode 2122 note: the smallest number is always in lower, so enumerating its partner fixes k; after sorting, two pointers pair each smallest unmatched number with the number 2k above ithttps://h30306.github.io/blog/leetcode/leetcode-3804/Sun, 11 Jan 2026 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/leetcode/leetcode-3804/LeetCode 3804 note: fix the left end and extend right, adding to the sum and to a set; count the subarray when the sum is in the sethttps://h30306.github.io/blog/leetcode/leetcode-3799/Sun, 04 Jan 2026 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/leetcode/leetcode-3799/LeetCode 3799 note: four nested levels pruned by corner letters; sorting the words first makes the output lexicographichttps://h30306.github.io/blog/leetcode/leetcode-2044/Tue, 29 Jul 2025 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/leetcode/leetcode-2044/LeetCode 2044 note: the maximum OR is the OR of everything; once backtracking reaches it, count the rest as 2^khttps://h30306.github.io/blog/leetcode/leetcode-2094/Mon, 12 May 2025 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/leetcode/leetcode-2094/LeetCode 2094 note: enumerate the even numbers 100 to 998 instead and check that each digit needed is available; Counter subtraction keeps only positiveshttps://h30306.github.io/blog/leetcode/leetcode-204/Fri, 11 Nov 2022 00:00:00 +0000hwork0511@gmail.com (Wei Yi Chung)https://h30306.github.io/blog/leetcode/leetcode-204/LeetCode 204 note: the sieve of Eratosthenes, crossing out multiples of each prime p starting at p², with the outer loop only up to √n