Date: 2026-06-06
Time: 18:02
This file implements the solution to LeetCode 1974: Minimum Time to Type Word Using Special Typewriter. It owns the single responsibility of computing the minimum number of seconds to type a given word on a circular typewriter where 26 lowercase letters are arranged in a ring (a-z wrapping back to a), and the pointer starts at 'a'.
Each second, you can either move the pointer one position clockwise/counterclockwise, or type the current character. The goal is to minimize total seconds.
Solution.minTimeToType(self, word: str) -> int — The sole method. Takes a lowercase word and returns the minimum seconds to type it.
curr (line 5): Tracks the pointer's current position as an integer offset from 'a' (0–25). Starts at 0 ('a').target (line 7): The position of the next character to type, computed as ord(ch) - ord('a').diff (line 8): The linear (non-wrapping) distance between the current position and the target.min(diff, 26 - diff) (line 9): The shorter of the two arcs around the circular alphabet. This is the core insight — on a ring of 26 elements, the shortest path is always min(|a - b|, 26 - |a - b|).+ 1 on line 9 accounts for the one second needed to actually type the character after arriving at it.Circular distance idiom: min(diff, 26 - diff) is the standard formula for shortest arc distance on a modular ring. This same pattern appears in distance-between-bus-stops/solution.py and single-row-keyboard/solution.py (without the circular wrap).
Greedy sequential processing: Each character is processed left-to-right with no lookahead. This is optimal because the pointer must visit each character in order — there's no way to benefit from reordering.
Imports: None. Pure algorithm, no standard library or external dependencies.
Imported by: minimum-time-to-type-word-using-special-typewriter/test_solution.py (the Imported By list in the prompt is the full test suite across the repo — each test file imports its own solution.py via a shared test harness pattern, not this specific file).
1. Initialize time = 0, curr = 0 (pointer at 'a').
2. For each character in word:
target position (0–25).diff = abs(target - curr) — the naive linear gap.min(diff, 26 - diff) + 1 to time — shortest arc + 1 second to type.curr = target.3. Return accumulated time.
For word = "abc": pointer moves a→a (0+1), a→b (1+1), b→c (1+1) = 5.
curr is always in [0, 25] — it's set directly from ord(ch) - ord('a') on valid lowercase input.[0, 13] (at most halfway around a 26-element ring), plus 1 for typing, so per-character cost is [1, 14].>= len(word) because every character costs at least 1 second to type even if the pointer is already there.None. The method assumes word consists of lowercase English letters per the LeetCode contract. Invalid input (uppercase, non-alpha, empty string) would either produce wrong results or raise a TypeError/incorrect computation silently.
single-row-keyboard/solution.py — Similar problem but on a linear (non-circular) keyboard; compare how the distance formula differsdistance-between-bus-stops/solution.py — Another circular-distance problem; uses the same min(d, total - d) idiom but over arbitrary weightsminimum-time-to-type-word-using-special-typewriter/test_solution.py — See which edge cases are tested (single char, full alphabet, repeated chars, max-distance jumps)circular-distance-problems — The min(diff, N - diff) pattern recurs across modular arithmetic problems (bus stops, rotating arrays, clock angles)min-time-typewriter-greedy-optimal — Processing characters left-to-right with shortest-arc moves is provably optimal; no lookahead or reordering can reduce total time.min-time-typewriter-per-char-bound — Each character contributes exactly min(|target - curr|, 26 - |target - curr|) + 1 seconds, bounded to [1, 14].min-time-typewriter-no-imports — The solution uses no imports and depends only on the ord builtin.min-time-typewriter-result-lower-bound — The return value is always >= len(word) because typing each character costs at least 1 second regardless of pointer position.