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Commit 9f4e15c

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Merge pull request #288 from hellomrsun/master
Add C# solutions
2 parents 7e24e8b + 1243c6f commit 9f4e15c

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public class RecentCounter {
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private Queue<int> queue;
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private int count;
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public RecentCounter() {
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count = 0;
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queue = new Queue<int>();
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}
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public int Ping(int t) {
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queue.Enqueue(t);
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while(t - queue.FirstOrDefault() > 3000)
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{
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queue.Dequeue();
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}
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return queue.Count();
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}
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}
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/**
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* Your RecentCounter object will be instantiated and called as such:
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* RecentCounter obj = new RecentCounter();
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* int param_1 = obj.Ping(t);
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*/

‎README.md

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https://leetcode.com
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## October LeetCoding Challenge
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Click [here](https://leetcode.com/explore/challenge/card/october-leetcoding-challenge/) for problem descriptions.
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Solutions in various programming languages are provided. Enjoy it.
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1. [Number of Recent Calls](https://github.com/AlgoStudyGroup/Leetcode/tree/master/October-LeetCoding-Challenge/01-Number-of-Recent-Calls) : Queue
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## September LeetCoding Challenge
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Click [here](https://leetcode.com/explore/challenge/card/september-leetcoding-challenge) for problem descriptions.
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19. [Sequential Digits](https://github.com/AlgoStudyGroup/Leetcode/tree/master/September-LeetCoding-Challenge/19-Sequential-Digits)
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23. [Gas Station](https://github.com/AlgoStudyGroup/Leetcode/tree/master/September-LeetCoding-Challenge/23-Gas-Station)
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28. [Subarray Product Less Than K](https://github.com/AlgoStudyGroup/Leetcode/tree/master/September-LeetCoding-Challenge/28-Subarray-Product-Less-Than-K)
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30. [First Missing Positive](https://github.com/AlgoStudyGroup/Leetcode/tree/master/September-LeetCoding-Challenge/30-First-Missing-Positive)
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## August LeetCoding Challenge
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Click [here](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge/) for problem descriptions.
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public class Solution {
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public int FirstMissingPositive(int[] nums) {
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int n = nums.Length;
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// 1. mark numbers (num < 0) and (num > n) with a special marker number (n+1)
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// (we can ignore those because if all number are > n then we'll simply return 1)
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for (int i = 0; i < n; i++)
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{
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if (nums[i] <= 0 || nums[i] > n)
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{
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nums[i] = n + 1;
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}
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}
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// note: all number in the array are now positive, and on the range 1..n+1
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// 2. mark each cell appearing in the array, by converting the index for that number to negative
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for (int i = 0; i < n; i++)
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{
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int num = Math.Abs(nums[i]);
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if (num > n)
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{
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continue;
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}
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num--; // -1 for zero index based array (so the number 1 will be at pos 0)
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if (nums[num] > 0)
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{ // prevents double negative operations
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nums[num] = -1 * nums[num];
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}
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}
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// 3. find the first cell which isn't negative (doesn't appear in the array)
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for (int i = 0; i < n; i++)
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{
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if (nums[i] >= 0)
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{
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return i + 1;
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}
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}
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// 4. no positive numbers were found, which means the array contains all numbers 1..n
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return n + 1;
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}
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}

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