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‎Problemset/1224-Maximum Equal Frequency/README.md

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# 1224. Maximum Equal Frequency
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Given an array `nums` of positive integers, return the longest possible length of an array prefix of `nums`, such that it is possible to remove **exactly one** element from this prefix so that every number that has appeared in it will have the same number of occurrences.
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If after removing one element there are no remaining elements, it's still considered that every appeared number has the same number of ocurrences (0).
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#### Example 1:
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<pre>
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<strong>Input:</strong> nums = [2,2,1,1,5,3,3,5]
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<strong>Output:</strong> 7
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<strong>Explanation:</strong> For the subarray [2,2,1,1,5,3,3] of length 7, if we remove nums[4] = 5, we will get [2,2,1,1,3,3], so that each number will appear exactly twice.
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</pre>
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#### Example 2:
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<pre>
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<strong>Input:</strong> nums = [1,1,1,2,2,2,3,3,3,4,4,4,5]
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<strong>Output:</strong> 13
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</pre>
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#### Constraints:
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* <code>2 <= nums.length <= 10<sup>5</sup></code>
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* <code>1 <= nums[i] <= 10<sup>5</sup></code>
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## Solutions (Rust)
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### 1. Solution
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```Rust
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use std::collections::HashMap;
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impl Solution {
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pub fn max_equal_freq(nums: Vec<i32>) -> i32 {
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let mut count_nums = HashMap::new();
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let mut count_ocurrences = HashMap::new();
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for &num in &nums {
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*count_nums.entry(num).or_insert(0) += 1;
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}
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for &ocurrence in count_nums.values() {
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*count_ocurrences.entry(ocurrence).or_insert(0) += 1;
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}
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for i in (0..nums.len()).rev() {
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if count_ocurrences.len() == 1 {
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let (&k0, &v0) = count_ocurrences.iter().next().unwrap();
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if k0 == 1 || v0 == 1 {
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return i as i32 + 1;
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}
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} else if count_ocurrences.len() == 2 {
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let (&k0, &v0) = count_ocurrences.iter().max().unwrap();
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let (&k1, &v1) = count_ocurrences.iter().min().unwrap();
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if (k1, v1) == (1, 1) || (k0 == k1 + 1 && v0 == 1) {
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return i as i32 + 1;
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}
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}
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*count_ocurrences.get_mut(&count_nums[&nums[i]]).unwrap() -= 1;
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if count_ocurrences.get(&(count_nums[&nums[i]])) == Some(&0) {
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count_ocurrences.remove(&count_nums[&nums[i]]);
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}
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*count_nums.get_mut(&nums[i]).unwrap() -= 1;
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if count_nums[&nums[i]] > 0 {
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*count_ocurrences.entry(count_nums[&nums[i]]).or_insert(0) += 1;
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}
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}
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1
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}
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}
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```

‎Problemset/1224-Maximum Equal Frequency/README_CN.md

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# 1224. 最大相等频率
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给你一个正整数数组 `nums`，请你帮忙从该数组中找出能满足下面要求的 **最长** 前缀，并返回该前缀的长度：
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* 从前缀中 **恰好删除一个** 元素后，剩下每个数字的出现次数都相同。
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如果删除这个元素后没有剩余元素存在，仍可认为每个数字都具有相同的出现次数（也就是 0 次）。
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#### 示例 1:
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<pre>
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<strong>输入:</strong> nums = [2,2,1,1,5,3,3,5]
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<strong>输出:</strong> 7
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<strong>解释:</strong> 对于长度为 7 的子数组 [2,2,1,1,5,3,3]，如果我们从中删去 nums[4] = 5，就可以得到 [2,2,1,1,3,3]，里面每个数字都出现了两次。
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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> nums = [1,1,1,2,2,2,3,3,3,4,4,4,5]
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<strong>输出:</strong> 13
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</pre>
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#### 提示:
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* <code>2 <= nums.length <= 10<sup>5</sup></code>
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* <code>1 <= nums[i] <= 10<sup>5</sup></code>
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## 题解 (Rust)
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### 1. 题解
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```Rust
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use std::collections::HashMap;
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impl Solution {
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pub fn max_equal_freq(nums: Vec<i32>) -> i32 {
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let mut count_nums = HashMap::new();
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let mut count_ocurrences = HashMap::new();
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for &num in &nums {
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*count_nums.entry(num).or_insert(0) += 1;
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}
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for &ocurrence in count_nums.values() {
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*count_ocurrences.entry(ocurrence).or_insert(0) += 1;
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}
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for i in (0..nums.len()).rev() {
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if count_ocurrences.len() == 1 {
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let (&k0, &v0) = count_ocurrences.iter().next().unwrap();
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if k0 == 1 || v0 == 1 {
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return i as i32 + 1;
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}
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} else if count_ocurrences.len() == 2 {
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let (&k0, &v0) = count_ocurrences.iter().max().unwrap();
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let (&k1, &v1) = count_ocurrences.iter().min().unwrap();
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if (k1, v1) == (1, 1) || (k0 == k1 + 1 && v0 == 1) {
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return i as i32 + 1;
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}
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}
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*count_ocurrences.get_mut(&count_nums[&nums[i]]).unwrap() -= 1;
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if count_ocurrences.get(&(count_nums[&nums[i]])) == Some(&0) {
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count_ocurrences.remove(&count_nums[&nums[i]]);
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}
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*count_nums.get_mut(&nums[i]).unwrap() -= 1;
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if count_nums[&nums[i]] > 0 {
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*count_ocurrences.entry(count_nums[&nums[i]]).or_insert(0) += 1;
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}
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}
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1
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}
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}
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```

‎Problemset/1224-Maximum Equal Frequency/Solution.rs

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use std::collections::HashMap;
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impl Solution {
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pub fn max_equal_freq(nums: Vec<i32>) -> i32 {
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let mut count_nums = HashMap::new();
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let mut count_ocurrences = HashMap::new();
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for &num in &nums {
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*count_nums.entry(num).or_insert(0) += 1;
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}
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for &ocurrence in count_nums.values() {
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*count_ocurrences.entry(ocurrence).or_insert(0) += 1;
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}
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for i in (0..nums.len()).rev() {
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if count_ocurrences.len() == 1 {
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let (&k0, &v0) = count_ocurrences.iter().next().unwrap();
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if k0 == 1 || v0 == 1 {
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return i as i32 + 1;
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}
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} else if count_ocurrences.len() == 2 {
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let (&k0, &v0) = count_ocurrences.iter().max().unwrap();
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let (&k1, &v1) = count_ocurrences.iter().min().unwrap();
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if (k1, v1) == (1, 1) || (k0 == k1 + 1 && v0 == 1) {
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return i as i32 + 1;
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}
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}
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*count_ocurrences.get_mut(&count_nums[&nums[i]]).unwrap() -= 1;
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if count_ocurrences.get(&(count_nums[&nums[i]])) == Some(&0) {
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count_ocurrences.remove(&count_nums[&nums[i]]);
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}
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*count_nums.get_mut(&nums[i]).unwrap() -= 1;
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if count_nums[&nums[i]] > 0 {
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*count_ocurrences.entry(count_nums[&nums[i]]).or_insert(0) += 1;
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}
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}
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1
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}
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}

‎README.md

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[1221][1221l]|[Split a String in Balanced Strings][1221] |![rb]&nbsp;&nbsp;![rs]
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[1222][1222l]|[Queens That Can Attack the King][1222] |![rs]
662662
[1223][1223l]|[Dice Roll Simulation][1223] |![rs]
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[1224][1224l]|[Maximum Equal Frequency][1224] |![rs]
663664
[1232][1232l]|[Check If It Is a Straight Line][1232] |![rs]
664665
[1233][1233l]|[Remove Sub-Folders from the Filesystem][1233] |![rs]
665666
[1234][1234l]|[Replace the Substring for Balanced String][1234] |![rb]&nbsp;&nbsp;![rs]
@@ -1957,6 +1958,7 @@
19571958
[1221]:Problemset/1221-Split%20a%20String%20in%20Balanced%20Strings/README.md#1221-split-a-string-in-balanced-strings
19581959
[1222]:Problemset/1222-Queens%20That%20Can%20Attack%20the%20King/README.md#1222-queens-that-can-attack-the-king
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[1223]:Problemset/1223-Dice%20Roll%20Simulation/README.md#1223-dice-roll-simulation
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[1224]:Problemset/1224-Maximum%20Equal%20Frequency/README.md#1224-maximum-equal-frequency
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[1232]:Problemset/1232-Check%20If%20It%20Is%20a%20Straight%20Line/README.md#1232-check-if-it-is-a-straight-line
19611963
[1233]:Problemset/1233-Remove%20Sub-Folders%20from%20the%20Filesystem/README.md#1233-remove-sub-folders-from-the-filesystem
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[1234]:Problemset/1234-Replace%20the%20Substring%20for%20Balanced%20String/README.md#1234-replace-the-substring-for-balanced-string
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[1221l]:https://leetcode.com/problems/split-a-string-in-balanced-strings/
32583260
[1222l]:https://leetcode.com/problems/queens-that-can-attack-the-king/
32593261
[1223l]:https://leetcode.com/problems/dice-roll-simulation/
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[1224l]:https://leetcode.com/problems/maximum-equal-frequency/
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[1232l]:https://leetcode.com/problems/check-if-it-is-a-straight-line/
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[1233l]:https://leetcode.com/problems/remove-sub-folders-from-the-filesystem/
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[1234l]:https://leetcode.com/problems/replace-the-substring-for-balanced-string/

‎README_CN.md

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[1221][1221l]|[分割平衡字符串][1221] |![rb]&nbsp;&nbsp;![rs]
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[1222][1222l]|[可以攻击国王的皇后][1222] |![rs]
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[1223][1223l]|[掷骰子模拟][1223] |![rs]
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[1224][1224l]|[最大相等频率][1224] |![rs]
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[1232][1232l]|[缀点成线][1232] |![rs]
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[1233][1233l]|[删除子文件夹][1233] |![rs]
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[1234][1234l]|[替换子串得到平衡字符串][1234] |![rb]&nbsp;&nbsp;![rs]
@@ -1957,6 +1958,7 @@
19571958
[1221]:Problemset/1221-Split%20a%20String%20in%20Balanced%20Strings/README_CN.md#1221-分割平衡字符串
19581959
[1222]:Problemset/1222-Queens%20That%20Can%20Attack%20the%20King/README_CN.md#1222-可以攻击国王的皇后
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[1223]:Problemset/1223-Dice%20Roll%20Simulation/README_CN.md#1223-掷骰子模拟
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[1224]:Problemset/1224-Maximum%20Equal%20Frequency/README_CN.md#1224-最大相等频率
19601962
[1232]:Problemset/1232-Check%20If%20It%20Is%20a%20Straight%20Line/README_CN.md#1232-缀点成线
19611963
[1233]:Problemset/1233-Remove%20Sub-Folders%20from%20the%20Filesystem/README_CN.md#1233-删除子文件夹
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[1234]:Problemset/1234-Replace%20the%20Substring%20for%20Balanced%20String/README_CN.md#1234-替换子串得到平衡字符串
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[1221l]:https://leetcode.cn/problems/split-a-string-in-balanced-strings/
32583260
[1222l]:https://leetcode.cn/problems/queens-that-can-attack-the-king/
32593261
[1223l]:https://leetcode.cn/problems/dice-roll-simulation/
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[1224l]:https://leetcode.cn/problems/maximum-equal-frequency/
32603263
[1232l]:https://leetcode.cn/problems/check-if-it-is-a-straight-line/
32613264
[1233l]:https://leetcode.cn/problems/remove-sub-folders-from-the-filesystem/
32623265
[1234l]:https://leetcode.cn/problems/replace-the-substring-for-balanced-string/

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