Shortest Distance to a Character

Given a stringS and a characterC, return an array of integers representing the shortest distance from the characterCin the string.

Example 1:

Input:
 S = "loveleetcode", C = 'e'

Output:
 [3, 2, 1, 0, 1, 0, 0, 1, 2, 2, 1, 0]

Note:

S string length is in [1, 10000].
C is a single character, and guaranteed to be in string S.
All letters in S and C are lowercase.

分析

左右各遍历一遍，得到min distance

class Solution:
    def shortestToChar(self, S: str, C: str) -> List[int]:        
        ll = len(S)
        res = [ll]*ll
        pos = -ll #注意此处取值弄成最大就好
        for i in range(ll):
            if S[i] == C:
                pos = i
                res[i] = 0
            else:
                res[i] = min(res[i],abs(pos - i))
        for i in range(ll-1,-1,-1):
            if S[i] == C:
                pos = i
                res[i] = 0
            else:
                res[i] = min(res[i],abs(pos - i))
        return res