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‎Problemset/2302-Count Subarrays With Score Less Than K/README.md

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# 2302. Count Subarrays With Score Less Than K
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The **score** of an array is defined as the **product** of its sum and its length.
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* For example, the score of `[1, 2, 3, 4, 5]` is `(1 + 2 + 3 + 4 + 5) * 5 = 75`.
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Given a positive integer array `nums` and an integer `k`, return *the **number of non-empty subarrays** of* `nums` *whose score is **strictly less** than* `k`.
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A **subarray** is a contiguous sequence of elements within an array.
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#### Example 1:
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<pre>
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<strong>Input:</strong> nums = [2,1,4,3,5], k = 10
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<strong>Output:</strong> 6
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<strong>Explanation:</strong>
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The 6 subarrays having scores less than 10 are:
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- [2] with score 2 * 1 = 2.
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- [1] with score 1 * 1 = 1.
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- [4] with score 4 * 1 = 4.
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- [3] with score 3 * 1 = 3.
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- [5] with score 5 * 1 = 5.
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- [2,1] with score (2 + 1) * 2 = 6.
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Note that subarrays such as [1,4] and [4,3,5] are not considered because their scores are 10 and 36 respectively, while we need scores strictly less than 10.
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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], k = 5
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<strong>Output:</strong> 5
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<strong>Explanation:</strong>
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Every subarray except [1,1,1] has a score less than 5.
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[1,1,1] has a score (1 + 1 + 1) * 3 = 9, which is greater than 5.
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Thus, there are 5 subarrays having scores less than 5.
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</pre>
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#### Constraints:
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* <code>1 <= nums.length <= 10<sup>5</sup></code>
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* <code>1 <= nums[i] <= 10<sup>5</sup></code>
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* <code>1 <= k <= 10<sup>15</sup></code>
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## Solutions (Rust)
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### 1. Solution
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```Rust
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impl Solution {
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pub fn count_subarrays(nums: Vec<i32>, k: i64) -> i64 {
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let mut prefix_sum = vec![0; nums.len() + 1];
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let mut ret = 0;
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for i in 0..nums.len() {
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prefix_sum[i + 1] = prefix_sum[i] + nums[i] as i64;
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}
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for i in 0..nums.len() {
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let mut lo = 0;
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let mut hi = i + 1;
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while lo < hi {
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let mid = (lo + hi) / 2;
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let score = (prefix_sum[i + 1] - prefix_sum[mid]) * (i + 1 - mid) as i64;
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if score < k {
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hi = mid;
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} else {
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lo = mid + 1;
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}
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}
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ret += (i + 1 - hi) as i64;
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}
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ret
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}
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}
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```

‎Problemset/2302-Count Subarrays With Score Less Than K/README_CN.md

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# 2302. 统计得分小于 K 的子数组数目
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一个数组的 **分数** 定义为数组之和 **乘以** 数组的长度。
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* 比方说，`[1, 2, 3, 4, 5]` 的分数为 `(1 + 2 + 3 + 4 + 5) * 5 = 75` 。
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给你一个正整数数组 `nums` 和一个整数 `k` ，请你返回 `nums` 中分数 **严格小于** `k` 的 **非空整数子数组数目**。
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**子数组** 是数组中的一个连续元素序列。
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#### 示例 1:
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<pre>
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<strong>输入:</strong> nums = [2,1,4,3,5], k = 10
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<strong>输出:</strong> 6
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<strong>解释:</strong>
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有 6 个子数组的分数小于 10 ：
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- [2] 分数为 2 * 1 = 2 。
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- [1] 分数为 1 * 1 = 1 。
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- [4] 分数为 4 * 1 = 4 。
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- [3] 分数为 3 * 1 = 3 。
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- [5] 分数为 5 * 1 = 5 。
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- [2,1] 分数为 (2 + 1) * 2 = 6 。
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注意，子数组 [1,4] 和 [4,3,5] 不符合要求，因为它们的分数分别为 10 和 36，但我们要求子数组的分数严格小于 10 。
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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], k = 5
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<strong>输出:</strong> 5
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<strong>解释:</strong>
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除了 [1,1,1] 以外每个子数组分数都小于 5 。
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[1,1,1] 分数为 (1 + 1 + 1) * 3 = 9 ，大于 5 。
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所以总共有 5 个子数组得分小于 5 。
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</pre>
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#### 提示:
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* <code>1 <= nums.length <= 10<sup>5</sup></code>
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* <code>1 <= nums[i] <= 10<sup>5</sup></code>
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* <code>1 <= k <= 10<sup>15</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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impl Solution {
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pub fn count_subarrays(nums: Vec<i32>, k: i64) -> i64 {
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let mut prefix_sum = vec![0; nums.len() + 1];
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let mut ret = 0;
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for i in 0..nums.len() {
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prefix_sum[i + 1] = prefix_sum[i] + nums[i] as i64;
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}
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for i in 0..nums.len() {
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let mut lo = 0;
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let mut hi = i + 1;
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while lo < hi {
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let mid = (lo + hi) / 2;
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let score = (prefix_sum[i + 1] - prefix_sum[mid]) * (i + 1 - mid) as i64;
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if score < k {
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hi = mid;
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} else {
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lo = mid + 1;
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}
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}
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ret += (i + 1 - hi) as i64;
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}
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ret
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}
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}
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```

‎Problemset/2302-Count Subarrays With Score Less Than K/Solution.rs

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impl Solution {
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pub fn count_subarrays(nums: Vec<i32>, k: i64) -> i64 {
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let mut prefix_sum = vec![0; nums.len() + 1];
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let mut ret = 0;
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for i in 0..nums.len() {
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prefix_sum[i + 1] = prefix_sum[i] + nums[i] as i64;
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}
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for i in 0..nums.len() {
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let mut lo = 0;
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let mut hi = i + 1;
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while lo < hi {
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let mid = (lo + hi) / 2;
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let score = (prefix_sum[i + 1] - prefix_sum[mid]) * (i + 1 - mid) as i64;
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if score < k {
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hi = mid;
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} else {
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lo = mid + 1;
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}
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}
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ret += (i + 1 - hi) as i64;
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}
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ret
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}
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}

‎README.md

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[2299][2299l]|[Strong Password Checker II][2299] |![rs]
14901490
[2300][2300l]|[Successful Pairs of Spells and Potions][2300] |![py]
14911491
[2301][2301l]|[Match Substring After Replacement][2301] |![rs]
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[2302][2302l]|[Count Subarrays With Score Less Than K][2302] |![rs]
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[2303][2303l]|[Calculate Amount Paid in Taxes][2303] |![rs]
14931494
[2304][2304l]|[Minimum Path Cost in a Grid][2304] |![rs]
14941495
[2306][2306l]|[Naming a Company][2306] |![py]
@@ -3169,6 +3170,7 @@
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[2299]:Problemset/2299-Strong%20Password%20Checker%20II/README.md#2299-strong-password-checker-ii
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[2300]:Problemset/2300-Successful%20Pairs%20of%20Spells%20and%20Potions/README.md#2300-successful-pairs-of-spells-and-potions
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[2301]:Problemset/2301-Match%20Substring%20After%20Replacement/README.md#2301-match-substring-after-replacement
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[2302]:Problemset/2302-Count%20Subarrays%20With%20Score%20Less%20Than%20K/README.md#2302-count-subarrays-with-score-less-than-k
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[2303]:Problemset/2303-Calculate%20Amount%20Paid%20in%20Taxes/README.md#2303-calculate-amount-paid-in-taxes
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[2304]:Problemset/2304-Minimum%20Path%20Cost%20in%20a%20Grid/README.md#2304-minimum-path-cost-in-a-grid
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[2306]:Problemset/2306-Naming%20a%20Company/README.md#2306-naming-a-company
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[2299l]:https://leetcode.com/problems/strong-password-checker-ii/
48444846
[2300l]:https://leetcode.com/problems/successful-pairs-of-spells-and-potions/
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[2301l]:https://leetcode.com/problems/match-substring-after-replacement/
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[2302l]:https://leetcode.com/problems/count-subarrays-with-score-less-than-k/
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[2303l]:https://leetcode.com/problems/calculate-amount-paid-in-taxes/
48474850
[2304l]:https://leetcode.com/problems/minimum-path-cost-in-a-grid/
48484851
[2306l]:https://leetcode.com/problems/naming-a-company/

‎README_CN.md

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[2299][2299l]|[强密码检验器 II][2299] |![rs]
14901490
[2300][2300l]|[咒语和药水的成功对数][2300] |![py]
14911491
[2301][2301l]|[替换字符后匹配][2301] |![rs]
1492+
[2302][2302l]|[统计得分小于 K 的子数组数目][2302] |![rs]
14921493
[2303][2303l]|[计算应缴税款总额][2303] |![rs]
14931494
[2304][2304l]|[网格中的最小路径代价][2304] |![rs]
14941495
[2306][2306l]|[公司命名][2306] |![py]
@@ -3169,6 +3170,7 @@
31693170
[2299]:Problemset/2299-Strong%20Password%20Checker%20II/README_CN.md#2299-强密码检验器-ii
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[2300]:Problemset/2300-Successful%20Pairs%20of%20Spells%20and%20Potions/README_CN.md#2300-咒语和药水的成功对数
31713172
[2301]:Problemset/2301-Match%20Substring%20After%20Replacement/README_CN.md#2301-替换字符后匹配
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[2302]:Problemset/2302-Count%20Subarrays%20With%20Score%20Less%20Than%20K/README_CN.md#2302-统计得分小于-k-的子数组数目
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[2303]:Problemset/2303-Calculate%20Amount%20Paid%20in%20Taxes/README_CN.md#2303-计算应缴税款总额
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[2304]:Problemset/2304-Minimum%20Path%20Cost%20in%20a%20Grid/README_CN.md#2304-网格中的最小路径代价
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[2306]:Problemset/2306-Naming%20a%20Company/README_CN.md#2306-公司命名
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[2299l]:https://leetcode.cn/problems/strong-password-checker-ii/
48444846
[2300l]:https://leetcode.cn/problems/successful-pairs-of-spells-and-potions/
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[2301l]:https://leetcode.cn/problems/match-substring-after-replacement/
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[2302l]:https://leetcode.cn/problems/count-subarrays-with-score-less-than-k/
48464849
[2303l]:https://leetcode.cn/problems/calculate-amount-paid-in-taxes/
48474850
[2304l]:https://leetcode.cn/problems/minimum-path-cost-in-a-grid/
48484851
[2306l]:https://leetcode.cn/problems/naming-a-company/

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