Leetcode 2914. Minimum Number of Changes to Make Binary String Beautiful

  • [Leetcode 2914. Minimum Number of Changes to Make Binary String Beautiful](#Leetcode 2914. Minimum Number of Changes to Make Binary String Beautiful)
    • [1. 解题思路](#1. 解题思路)
    • [2. 代码实现](#2. 代码实现)

1. 解题思路

这一题思路很简单,就是一个贪婪算法。

显然,从头往后考察每一个字符,如果它与前一个字符不相同,那么我们必然只有两个选择:

  1. 如果前面刚好为偶数个字符,那么直接在此处截断即可;
  2. 如果前面为奇数个字符,那么必然要将这个字符反转,此时同样可以在此处截断,因为不会影响后续结果。

这么一来,事实上贪婪算法的结果就必然是最小结果,我们直接给出答案即可。

2. 代码实现

给出python代码实现如下:

python 复制代码
class Solution:
    def minChanges(self, s: str) -> int:
        ans = 0
        pre, cnt = "", 0
        for ch in s:
            if ch == pre:
                cnt += 1
            else:
                if cnt % 2 == 0:
                    pre = ch
                    cnt = 1
                else:
                    ans += 1
                    cnt = 0
        return ans

提交代码评测得到:耗时72ms,占用内存17.3MB。

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