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feat: add solutions to lc problems: No.2848~2850 (#1593)
* No.2848.Points That Intersect With Cars * No.2849.Determine if a Cell Is Reachable at a Given Time * No.2850.Minimum Moves to Spread Stones Over Grid
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‎solution/2800-2899/2848.Points That Intersect With Cars/README.md

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# [2848. 与车相交的点](https://leetcode.cn/problems/points-that-intersect-with-cars)
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[English Version](/solution/2800-2899/2848.Points%20That%20Intersect%20With%20Cars/README_EN.md)
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## 题目描述
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<!-- 这里写题目描述 -->
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<p>给你一个下标从 <strong>0</strong> 开始的二维整数数组 <code>nums</code> 表示汽车停放在数轴上的坐标。对于任意下标 <code>i</code>，<code>nums[i] = [start<sub>i</sub>, end<sub>i</sub>]</code> ，其中 <code>start<sub>i</sub></code> 是第 <code>i</code> 辆车的起点，<code>end<sub>i</sub></code> 是第 <code>i</code> 辆车的终点。</p>
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<p>返回数轴上被车 <strong>任意部分</strong> 覆盖的整数点的数目。</p>
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<p>&nbsp;</p>
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<p><strong class="example">示例 1：</strong></p>
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<pre>
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<strong>输入：</strong>nums = [[3,6],[1,5],[4,7]]
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<strong>输出：</strong>7
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<strong>解释：</strong>从 1 到 7 的所有点都至少与一辆车相交，因此答案为 7 。
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</pre>
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<p><strong class="example">示例 2：</strong></p>
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<pre>
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<strong>输入：</strong>nums = [[1,3],[5,8]]
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<strong>输出：</strong>7
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<strong>解释：</strong>1、2、3、5、6、7、8 共计 7 个点满足至少与一辆车相交，因此答案为 7 。
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</pre>
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<p>&nbsp;</p>
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<p><strong>提示：</strong></p>
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<ul>
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<li><code>1 &lt;= nums.length &lt;= 100</code></li>
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<li><code>nums[i].length == 2</code></li>
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<li><code><font face="monospace">1 &lt;= start<sub>i</sub>&nbsp;&lt;= end<sub>i</sub>&nbsp;&lt;= 100</font></code></li>
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</ul>
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## 解法
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<!-- 这里可写通用的实现逻辑 -->
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**方法一：差分数组**
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我们创建一个长度为 $110$ 的差分数组 $d$，然后遍历给定的数组，对于每个区间 $[a, b]$，我们令 $d[a]$ 增加 $1$，$d[b + 1]$ 减少 $1$。最后我们遍历差分数组 $d$，求每个位置的前缀和 $s$，如果 $s > 0$，则说明该位置被覆盖，我们将答案增加 $1$。
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时间复杂度 $O(n)$，空间复杂度 $O(M)$。其中 $n$ 是给定数组的长度，而 $M$ 是数组中元素的最大值。
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<!-- tabs:start -->
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### **Python3**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```python
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class Solution:
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def numberOfPoints(self, nums: List[List[int]]) -> int:
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d = [0] * 110
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for a, b in nums:
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d[a] += 1
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d[b + 1] -= 1
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return sum(s > 0 for s in accumulate(d))
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```
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### **Java**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```java
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class Solution {
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public int numberOfPoints(List<List<Integer>> nums) {
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int[] d = new int[110];
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for (var e : nums) {
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d[e.get(0)]++;
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d[e.get(1) + 1]--;
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}
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int ans = 0, s = 0;
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for (int x : d) {
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s += x;
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if (s > 0) {
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ans++;
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}
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}
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return ans;
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}
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}
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```
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### **C++**
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```cpp
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class Solution {
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public:
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int numberOfPoints(vector<vector<int>>& nums) {
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int d[110]{};
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for (auto& e : nums) {
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d[e[0]]++;
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d[e[1] + 1]--;
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}
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int ans = 0, s = 0;
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for (int x : d) {
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s += x;
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ans += s > 0;
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}
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return ans;
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}
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};
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```
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### **Go**
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```go
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func numberOfPoints(nums [][]int) (ans int) {
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d := [110]int{}
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for _, e := range nums {
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d[e[0]]++
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d[e[1]+1]--
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}
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s := 0
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for _, x := range d {
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s += x
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if s > 0 {
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ans++
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}
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}
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return
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}
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```
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### **TypeScript**
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```ts
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function numberOfPoints(nums: number[][]): number {
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const d: number[] = Array(110).fill(0);
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for (const [a, b] of nums) {
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d[a]++;
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d[b + 1]--;
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}
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let ans = 0;
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let s = 0;
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for (const x of d) {
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s += x;
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if (s > 0) {
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ans++;
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}
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}
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return ans;
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}
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```
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### **...**
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```
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```
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<!-- tabs:end -->

‎solution/2800-2899/2848.Points That Intersect With Cars/README_EN.md

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# [2848. Points That Intersect With Cars](https://leetcode.com/problems/points-that-intersect-with-cars)
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[中文文档](/solution/2800-2899/2848.Points%20That%20Intersect%20With%20Cars/README.md)
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## Description
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<p>You are given a <strong>0-indexed</strong> 2D integer array <code>nums</code> representing the coordinates of the cars parking on a number line. For any index <code>i</code>, <code>nums[i] = [start<sub>i</sub>, end<sub>i</sub>]</code> where <code>start<sub>i</sub></code> is the starting point of the <code>i<sup>th</sup></code> car and <code>end<sub>i</sub></code> is the ending point of the <code>i<sup>th</sup></code> car.</p>
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<p>Return <em>the number of integer points on the line that are covered with <strong>any part</strong> of a car.</em></p>
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<p>&nbsp;</p>
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<p><strong class="example">Example 1:</strong></p>
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<pre>
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<strong>Input:</strong> nums = [[3,6],[1,5],[4,7]]
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<strong>Output:</strong> 7
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<strong>Explanation:</strong> All the points from 1 to 7 intersect at least one car, therefore the answer would be 7.
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</pre>
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<p><strong class="example">Example 2:</strong></p>
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<pre>
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<strong>Input:</strong> nums = [[1,3],[5,8]]
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<strong>Output:</strong> 7
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<strong>Explanation:</strong> Points intersecting at least one car are 1, 2, 3, 5, 6, 7, 8. There are a total of 7 points, therefore the answer would be 7.
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</pre>
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<p>&nbsp;</p>
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<p><strong>Constraints:</strong></p>
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<ul>
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<li><code>1 &lt;= nums.length &lt;= 100</code></li>
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<li><code>nums[i].length == 2</code></li>
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<li><code><font face="monospace">1 &lt;= start<sub>i</sub>&nbsp;&lt;= end<sub>i</sub>&nbsp;&lt;= 100</font></code></li>
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</ul>
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## Solutions
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<!-- tabs:start -->
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### **Python3**
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```python
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class Solution:
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def numberOfPoints(self, nums: List[List[int]]) -> int:
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d = [0] * 110
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for a, b in nums:
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d[a] += 1
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d[b + 1] -= 1
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return sum(s > 0 for s in accumulate(d))
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```
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### **Java**
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```java
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class Solution {
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public int numberOfPoints(List<List<Integer>> nums) {
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int[] d = new int[110];
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for (var e : nums) {
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d[e.get(0)]++;
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d[e.get(1) + 1]--;
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}
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int ans = 0, s = 0;
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for (int x : d) {
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s += x;
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if (s > 0) {
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ans++;
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}
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}
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return ans;
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}
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}
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```
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### **C++**
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```cpp
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class Solution {
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public:
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int numberOfPoints(vector<vector<int>>& nums) {
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int d[110]{};
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for (auto& e : nums) {
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d[e[0]]++;
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d[e[1] + 1]--;
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}
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int ans = 0, s = 0;
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for (int x : d) {
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s += x;
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ans += s > 0;
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}
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return ans;
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}
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};
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```
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### **Go**
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```go
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func numberOfPoints(nums [][]int) (ans int) {
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d := [110]int{}
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for _, e := range nums {
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d[e[0]]++
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d[e[1]+1]--
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}
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s := 0
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for _, x := range d {
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s += x
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if s > 0 {
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ans++
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}
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}
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return
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}
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```
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### **TypeScript**
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```ts
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function numberOfPoints(nums: number[][]): number {
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const d: number[] = Array(110).fill(0);
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for (const [a, b] of nums) {
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d[a]++;
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d[b + 1]--;
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}
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let ans = 0;
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let s = 0;
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for (const x of d) {
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s += x;
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if (s > 0) {
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ans++;
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}
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}
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return ans;
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}
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```
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### **...**
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```
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```
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<!-- tabs:end -->

‎solution/2800-2899/2848.Points That Intersect With Cars/Solution.cpp

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class Solution {
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public:
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int numberOfPoints(vector<vector<int>>& nums) {
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int d[110]{};
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for (auto& e : nums) {
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d[e[0]]++;
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d[e[1] + 1]--;
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}
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int ans = 0, s = 0;
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for (int x : d) {
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s += x;
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ans += s > 0;
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}
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return ans;
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}
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};

‎solution/2800-2899/2848.Points That Intersect With Cars/Solution.go

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func numberOfPoints(nums [][]int) (ans int) {
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d := [110]int{}
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for _, e := range nums {
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d[e[0]]++
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d[e[1]+1]--
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}
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s := 0
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for _, x := range d {
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s += x
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if s > 0 {
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ans++
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}
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}
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return
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}

‎solution/2800-2899/2848.Points That Intersect With Cars/Solution.java

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class Solution {
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public int numberOfPoints(List<List<Integer>> nums) {
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int[] d = new int[110];
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for (var e : nums) {
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d[e.get(0)]++;
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d[e.get(1) + 1]--;
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}
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int ans = 0, s = 0;
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for (int x : d) {
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s += x;
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if (s > 0) {
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ans++;
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}
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}
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return ans;
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}
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}

‎solution/2800-2899/2848.Points That Intersect With Cars/Solution.py

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class Solution:
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def numberOfPoints(self, nums: List[List[int]]) -> int:
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d = [0] * 110
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for a, b in nums:
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d[a] += 1
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d[b + 1] -= 1
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return sum(s > 0 for s in accumulate(d))

‎solution/2800-2899/2848.Points That Intersect With Cars/Solution.ts

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function numberOfPoints(nums: number[][]): number {
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const d: number[] = Array(110).fill(0);
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for (const [a, b] of nums) {
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d[a]++;
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d[b + 1]--;
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}
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let ans = 0;
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let s = 0;
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for (const x of d) {
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s += x;
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if (s > 0) {
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ans++;
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}
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}
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return ans;
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}

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