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Tested Python solution for LeetCode 821 with 20 pytest cases. Generate a practice environment with lcpy.
lcpy gen -n 821 # by problem number
lcpy gen -s shortest_distance_to_a_character # by problem name
s and a character c that occurs in s, return an array of integers answer where answer.length == s.length and answer[i] is the distance from index i to the closest occurrence of character c in s.
The distance between two indices i and j is abs(i - j), where abs is the absolute value function.
Input: s = "loveleetcode", c = "e"
Output: [3,2,1,0,1,0,0,1,2,2,1,0]
Input: s = "aaab", c = "b"
Output: [3,2,1,0]
class Solution:
# Time: O(n)
# Space: O(n) for the output array
def shortest_to_char(self, s: str, c: str) -> list[int]:
n = len(s)
answer = [n] * n
prev = -n
for i, char in enumerate(s):
if char == c:
prev = i
answer[i] = i - prev
prev = 2 * n
for i in range(n - 1, -1, -1):
if s[i] == c:
prev = i
answer[i] = min(answer[i], prev - i)
return answer
| Time | Space |
|---|---|
| O(n) | O(n) for the output array |