1576. Replace All ?'s to Avoid Consecutive Repeating Characters

class Solution:
    def modifyString(self, s: str) -> str:
        """tc O(N)  sc O(N)
        
        """
        n = len(s)
        res = []
        for i in range(n):
            x= y = '?'
            if s[i] == '?':
                if i > 0:
                    l = i-1
                    x = res[l]
  
                if i+1 < n:
                    r = i +1 
                    y = s[r]
                tmp = 'a'
                while tmp == y or tmp == x: 
                    tmp = chr((97+randint(0,25)%26))
                res.append(tmp)
            else:
                res.append(s[i])
        return ''.join(res)

class Solution:
    def modifyString(self, s: str) -> str:
        s = list(s)
        for i in range(len(s)):
            if s[i] == "?": 
                for c in "abc": 
                    if (i == 0 or s[i-1] != c) and (i+1 == len(s) or s[i+1] != c): 
                        s[i] = c
                        break 
        return "".join(s)