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‎Problemset/1202-Smallest String With Swaps/README.md

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# 1202. Smallest String With Swaps
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You are given a string `s`, and an array of pairs of indices in the string `pairs` where `pairs[i] = [a, b]` indicates 2 indices(0-indexed) of the string.
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You can swap the characters at any pair of indices in the given `pairs` **any number of times**.
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Return the lexicographically smallest string that `s` can be changed to after using the swaps.
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#### Example 1:
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<pre>
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<strong>Input:</strong> s = "dcab", pairs = [[0,3],[1,2]]
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<strong>Output:</strong> "bacd"
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<strong>Explanation:</strong>
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Swap s[0] and s[3], s = "bcad"
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Swap s[1] and s[2], s = "bacd"
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</pre>
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#### Example 2:
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<pre>
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<strong>Input:</strong> s = "dcab", pairs = [[0,3],[1,2],[0,2]]
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<strong>Output:</strong> "abcd"
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<strong>Explanation:</strong>
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Swap s[0] and s[3], s = "bcad"
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Swap s[0] and s[2], s = "acbd"
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Swap s[1] and s[2], s = "abcd"
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</pre>
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#### Example 3:
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<pre>
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<strong>Input:</strong> s = "cba", pairs = [[0,1],[1,2]]
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<strong>Output:</strong> "abc"
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<strong>Explanation:</strong>
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Swap s[0] and s[1], s = "bca"
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Swap s[1] and s[2], s = "bac"
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Swap s[0] and s[1], s = "abc"
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</pre>
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#### Constraints:
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* `1 <= s.length <= 10^5`
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* `0 <= pairs.length <= 10^5`
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* `0 <= pairs[i][0], pairs[i][1] < s.length`
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* `s` only contains lower case English letters.
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## Solutions (Python)
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### 1. Solution
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```Python
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class Solution:
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def smallestStringWithSwaps(self, s: str, pairs: List[List[int]]) -> str:
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parent = list(range(len(s)))
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groups = {}
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chars = []
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for a, b in pairs:
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while parent[a] != parent[parent[a]]:
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parent[a] = parent[parent[a]]
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while parent[b] != parent[parent[b]]:
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parent[b] = parent[parent[b]]
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if parent[a] < parent[b]:
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parent[parent[b]] = parent[a]
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else:
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parent[parent[a]] = parent[b]
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for i in range(len(s)):
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while parent[i] != parent[parent[i]]:
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parent[i] = parent[parent[i]]
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if parent[i] not in groups:
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groups[parent[i]] = []
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groups[parent[i]].append(i)
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for group in groups:
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groups[group].sort(key=lambda i: -ord(s[i]))
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for i in range(len(s)):
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chars.append(s[groups[parent[i]].pop()])
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return ''.join(chars)
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```

‎Problemset/1202-Smallest String With Swaps/README_CN.md

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# 1202. 交换字符串中的元素
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给你一个字符串 `s`，以及该字符串中的一些「索引对」数组 `pairs`，其中 `pairs[i] = [a, b]` 表示字符串中的两个索引（编号从 0 开始）。
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你可以 **任意多次交换** 在 `pairs` 中任意一对索引处的字符。
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返回在经过若干次交换后，`s` 可以变成的按字典序最小的字符串。
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#### 示例 1:
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<pre>
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<strong>输入:</strong> s = "dcab", pairs = [[0,3],[1,2]]
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<strong>输出:</strong> "bacd"
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<strong>解释:</strong>
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交换 s[0] 和 s[3], s = "bcad"
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交换 s[1] 和 s[2], s = "bacd"
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</pre>
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#### 示例 2:
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<pre>
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<strong>输入:</strong> s = "dcab", pairs = [[0,3],[1,2],[0,2]]
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<strong>输出:</strong> "abcd"
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<strong>解释:</strong>
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交换 s[0] 和 s[3], s = "bcad"
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交换 s[0] 和 s[2], s = "acbd"
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交换 s[1] 和 s[2], s = "abcd"
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</pre>
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#### 示例 3:
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<pre>
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<strong>输入:</strong> s = "cba", pairs = [[0,1],[1,2]]
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<strong>输出:</strong> "abc"
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<strong>解释:</strong>
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交换 s[0] 和 s[1], s = "bca"
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交换 s[1] 和 s[2], s = "bac"
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交换 s[0] 和 s[1], s = "abc"
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</pre>
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#### Constraints:
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* `1 <= s.length <= 10^5`
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* `0 <= pairs.length <= 10^5`
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* `0 <= pairs[i][0], pairs[i][1] < s.length`
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* `s` 中只含有小写英文字母
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## 题解 (Python)
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### 1. 题解
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```Python
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class Solution:
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def smallestStringWithSwaps(self, s: str, pairs: List[List[int]]) -> str:
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parent = list(range(len(s)))
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groups = {}
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chars = []
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for a, b in pairs:
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while parent[a] != parent[parent[a]]:
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parent[a] = parent[parent[a]]
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while parent[b] != parent[parent[b]]:
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parent[b] = parent[parent[b]]
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if parent[a] < parent[b]:
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parent[parent[b]] = parent[a]
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else:
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parent[parent[a]] = parent[b]
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for i in range(len(s)):
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while parent[i] != parent[parent[i]]:
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parent[i] = parent[parent[i]]
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if parent[i] not in groups:
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groups[parent[i]] = []
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groups[parent[i]].append(i)
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for group in groups:
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groups[group].sort(key=lambda i: -ord(s[i]))
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for i in range(len(s)):
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chars.append(s[groups[parent[i]].pop()])
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return ''.join(chars)
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```

‎Problemset/1202-Smallest String With Swaps/Solution.py

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class Solution:
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def smallestStringWithSwaps(self, s: str, pairs: List[List[int]]) -> str:
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parent = list(range(len(s)))
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groups = {}
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chars = []
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for a, b in pairs:
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while parent[a] != parent[parent[a]]:
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parent[a] = parent[parent[a]]
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while parent[b] != parent[parent[b]]:
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parent[b] = parent[parent[b]]
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if parent[a] < parent[b]:
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parent[parent[b]] = parent[a]
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else:
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parent[parent[a]] = parent[b]
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for i in range(len(s)):
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while parent[i] != parent[parent[i]]:
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parent[i] = parent[parent[i]]
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if parent[i] not in groups:
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groups[parent[i]] = []
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groups[parent[i]].append(i)
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for group in groups:
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groups[group].sort(key=lambda i: -ord(s[i]))
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for i in range(len(s)):
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chars.append(s[groups[parent[i]].pop()])
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return ''.join(chars)

‎README.md

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[1190][1190l]|[Reverse Substrings Between Each Pair of Parentheses][1190] |![rs]
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[1191][1191l]|[K-Concatenation Maximum Sum][1191] |![rb]&nbsp;&nbsp;![rs]
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[1200][1200l]|[Minimum Absolute Difference][1200] |![rs]
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[1202][1202l]|[Smallest String With Swaps][1202] |![py]
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[1207][1207l]|[Unique Number of Occurrences][1207] |![rs]
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[1208][1208l]|[Get Equal Substrings Within Budget][1208] |![rb]&nbsp;&nbsp;![rs]
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[1209][1209l]|[Remove All Adjacent Duplicates in String II][1209] |![rs]
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[1190]:Problemset/1190-Reverse%20Substrings%20Between%20Each%20Pair%20of%20Parentheses/README.md#1190-reverse-substrings-between-each-pair-of-parentheses
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[1191]:Problemset/1191-K-Concatenation%20Maximum%20Sum/README.md#1191-k-concatenation-maximum-sum
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[1200]:Problemset/1200-Minimum%20Absolute%20Difference/README.md#1200-minimum-absolute-difference
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[1202]:Problemset/1202-Smallest%20String%20With%20Swaps/README.md#1202-smallest-string-with-swaps
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[1207]:Problemset/1207-Unique%20Number%20of%20Occurrences/README.md#1207-unique-number-of-occurrences
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[1208]:Problemset/1208-Get%20Equal%20Substrings%20Within%20Budget/README.md#1208-get-equal-substrings-within-budget
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[1209]:Problemset/1209-Remove%20All%20Adjacent%20Duplicates%20in%20String%20II/README.md#1209-remove-all-adjacent-duplicates-in-string-ii
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[1190l]:https://leetcode.com/problems/reverse-substrings-between-each-pair-of-parentheses/
31063108
[1191l]:https://leetcode.com/problems/k-concatenation-maximum-sum/
31073109
[1200l]:https://leetcode.com/problems/minimum-absolute-difference/
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[1202l]:https://leetcode.com/problems/smallest-string-with-swaps/
31083111
[1207l]:https://leetcode.com/problems/unique-number-of-occurrences/
31093112
[1208l]:https://leetcode.com/problems/get-equal-substrings-within-budget/
31103113
[1209l]:https://leetcode.com/problems/remove-all-adjacent-duplicates-in-string-ii/

‎README_CN.md

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[1190][1190l]|[反转每对括号间的子串][1190] |![rs]
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[1191][1191l]|[K 次串联后最大子数组之和][1191] |![rb]&nbsp;&nbsp;![rs]
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[1200][1200l]|[最小绝对差][1200] |![rs]
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[1202][1202l]|[交换字符串中的元素][1202] |![py]
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[1207][1207l]|[独一无二的出现次数][1207] |![rs]
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[1208][1208l]|[尽可能使字符串相等][1208] |![rb]&nbsp;&nbsp;![rs]
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[1209][1209l]|[删除字符串中的所有相邻重复项 II][1209] |![rs]
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[1190]:Problemset/1190-Reverse%20Substrings%20Between%20Each%20Pair%20of%20Parentheses/README_CN.md#1190-反转每对括号间的子串
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[1191]:Problemset/1191-K-Concatenation%20Maximum%20Sum/README_CN.md#1191-k-次串联后最大子数组之和
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[1200]:Problemset/1200-Minimum%20Absolute%20Difference/README_CN.md#1200-最小绝对差
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[1202]:Problemset/1202-Smallest%20String%20With%20Swaps/README_CN.md#1202-交换字符串中的元素
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[1207]:Problemset/1207-Unique%20Number%20of%20Occurrences/README_CN.md#1207-独一无二的出现次数
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[1208]:Problemset/1208-Get%20Equal%20Substrings%20Within%20Budget/README_CN.md#1208-尽可能使字符串相等
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[1209]:Problemset/1209-Remove%20All%20Adjacent%20Duplicates%20in%20String%20II/README_CN.md#1209-删除字符串中的所有相邻重复项-ii
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31053107
[1190l]:https://leetcode.cn/problems/reverse-substrings-between-each-pair-of-parentheses/
31063108
[1191l]:https://leetcode.cn/problems/k-concatenation-maximum-sum/
31073109
[1200l]:https://leetcode.cn/problems/minimum-absolute-difference/
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[1202l]:https://leetcode.cn/problems/smallest-string-with-swaps/
31083111
[1207l]:https://leetcode.cn/problems/unique-number-of-occurrences/
31093112
[1208l]:https://leetcode.cn/problems/get-equal-substrings-within-budget/
31103113
[1209l]:https://leetcode.cn/problems/remove-all-adjacent-duplicates-in-string-ii/

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