README ¶
1208. Get Equal Substrings Within Budget
题目
You are given two strings s
and t
of the same length. You want to change s
to t
. Changing the i
-th character of s
to i
-th character of t
costs |s[i] - t[i]|
that is, the absolute difference between the ASCII values of the characters.
You are also given an integer maxCost
.
Return the maximum length of a substring of s
that can be changed to be the same as the corresponding substring of t
with a cost less than or equal to maxCost
.
If there is no substring from s
that can be changed to its corresponding substring from t
, return 0
.
Example 1:
Input: s = "abcd", t = "bcdf", maxCost = 3
Output: 3
Explanation: "abc" of s can change to "bcd". That costs 3, so the maximum length is 3.
Example 2:
Input: s = "abcd", t = "cdef", maxCost = 3
Output: 1
Explanation: Each character in s costs 2 to change to charactor in t, so the maximum length is 1.
Example 3:
Input: s = "abcd", t = "acde", maxCost = 0
Output: 1
Explanation: You can't make any change, so the maximum length is 1.
Constraints:
1 <= s.length, t.length <= 10^5
0 <= maxCost <= 10^6
s
andt
only contain lower case English letters.
题目大意
给你两个长度相同的字符串,s 和 t。将 s 中的第 i 个字符变到 t 中的第 i 个字符需要 |s[i] - t[i]| 的开销(开销可能为 0),也就是两个字符的 ASCII 码值的差的绝对值。
用于变更字符串的最大预算是 maxCost。在转化字符串时,总开销应当小于等于该预算,这也意味着字符串的转化可能是不完全的。如果你可以将 s 的子字符串转化为它在 t 中对应的子字符串,则返回可以转化的最大长度。如果 s 中没有子字符串可以转化成 t 中对应的子字符串,则返回 0。
提示:
- 1 <= s.length, t.length <= 10^5
- 0 <= maxCost <= 10^6
- s 和 t 都只含小写英文字母。
解题思路
- 给出 2 个字符串
s
和t
和一个“预算”,要求把“预算”尽可能的花完,s
中最多连续有几个字母能变成t
中的字母。“预算”的定义是:|s[i] - t[i]| 。 - 这一题是滑动窗口的题目,滑动窗口右边界每移动一格,就减少一定的预算,直到预算不能减少,再移动滑动窗口的左边界,这个时候注意要把预算还原回去。当整个窗口把字符
s
或t
都滑动完了的时候,取出滑动过程中窗口的最大值即为结果。
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