LeetCode

LeetCode 3800 note: split mismatches into two kinds; pair different kinds with a swap, same kinds with cross + swap, flip any leftover, and compare each against two flips

LeetCode 3799 note: four nested levels pruned by corner letters; sorting the words first makes the output lexicographic

LeetCode 3798 note: parity depends only on the last digit, so just delete trailing 1s; keeping more digits is larger

LeetCode 2953 note: split where neighboring letters differ by more than 2; in each segment enumerate the number of distinct letters d, slide a fixed window of d × k, and track how many letters appear exactly k times

LeetCode 2269 note: convert the number to a string and check every length-k substring; 0 cannot be a divisor

LeetCode 2200 note: extend each key k positions both ways, and keep a pointer to how far output has gone so overlapping ranges are not emitted twice

LeetCode 2156 note: the first character has weight p^0, so sliding right to left needs only multiply by p, add the new character, and subtract the outgoing one times p^k; the modulus may not be prime, so no modular inverse

LeetCode 1016 note: s has at most 1000 characters, so there are few substrings of any fixed length and a large n must be False; checking from n downward fails fast, or extend up to 30 bits from each start to collect every value <= n

LeetCode 3796 note: each position’s bound is the min of its own limit, the left bound + difference and the right bound + difference; one pass each way

LeetCode 3795 note: a shortest-window slide where each value counts once; track each value’s last position, and subtract the left value only if it was the last occurrence

LeetCode 3794 note: one line with slicing; a hand-written two-pointer version must convert the string to a list first

LeetCode 2653 note: values are only -50 to 50, so the fixed window keeps a count array, and each window accumulates upward from -50 to find the x-th smallest negative