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yanglbmeyanglbme
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Merge pull request #245 from kfstorm/add_csharp
Import C# solutions from https://github.com/kfstorm/LeetCode
2 parents 04785c8 + 545e909 commit d7f977e

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‎solution/0001.Two Sum/Solution.cs

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using System.Collections.Generic;
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public class Solution {
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public int[] TwoSum(int[] nums, int target) {
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var dict = new Dictionary<int, int>();
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for (var i = 0; i < nums.Length; ++i)
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{
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int index;
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if (dict.TryGetValue(target - nums[i], out index))
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{
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return new [] { index, i};
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}
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if (!dict.ContainsKey(nums[i]))
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{
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dict.Add(nums[i], i);
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}
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}
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return null;
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}
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}

‎solution/0002.Add Two Numbers/Solution.cs

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public class Solution {
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public ListNode AddTwoNumbers(ListNode l1, ListNode l2) {
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return AddInternal(l1, l2, false);
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}
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private ListNode AddInternal(ListNode l1, ListNode l2, bool plusOne)
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{
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if (l1 == null && l2 == null)
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{
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if (plusOne)
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{
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return new ListNode(1);
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}
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return null;
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}
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var val = (l1 == null ? 0 : l1.val) + (l2 == null ? 0 : l2.val) + (plusOne ? 1 : 0);
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plusOne = val >= 10;
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val %= 10;
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return new ListNode(val)
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{
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//next = AddInternal(l1?.next, l2?.next, plusOne);
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next = AddInternal(l1 == null ? null : l1.next, l2 == null ? null : l2.next, plusOne)
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};
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}
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}

‎solution/0003.Longest Substring Without Repeating Characters/Solution.cs

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using System.Collections.Generic;
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public class Solution {
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public int LengthOfLongestSubstring(string s) {
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var hashSet = new HashSet<char>();
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var maxLength = 0;
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int i = 0, j = 0;
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while (i < s.Length)
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{
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while (hashSet.Contains(s[i]))
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{
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hashSet.Remove(s[j++]);
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}
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hashSet.Add(s[i++]);
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if (i - j > maxLength)
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{
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maxLength = i - j;
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}
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}
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return maxLength;
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}
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}

‎solution/0004.Median of Two Sorted Arrays/Solution.cs

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using System;
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using System.Linq;
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class Range
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{
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public static Range Empty = new Range(new int[0], 0, -1);
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public readonly int[] Numbers;
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public readonly int LeftIndex;
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public readonly int RightIndex;
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public int Count { get { return RightIndex - LeftIndex + 1; } }
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public int this[int index]
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{
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get
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{
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if (index >= Count)
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{
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throw new IndexOutOfRangeException();
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}
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return Numbers[LeftIndex + index];
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}
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}
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public Range(int[] numbers) : this(numbers, 0, numbers.Length - 1)
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{
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}
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public Range(int[] numbers, int leftIndex, int rightIndex)
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{
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Numbers = numbers;
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LeftIndex = leftIndex;
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RightIndex = rightIndex;
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if (RightIndex < LeftIndex) RightIndex = LeftIndex - 1;
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}
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public Range GetSubRange(int lowerBound, int upperBound)
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{
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if (lowerBound > upperBound) return Empty;
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var leftIndex = lowerBound == int.MinValue ? LeftIndex : Search(lowerBound);
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var rightIndex = upperBound == int.MaxValue ? RightIndex : Search(upperBound + 1) - 1;
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return new Range(Numbers, leftIndex, rightIndex);
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}
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private int Search(int target)
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{
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var l = 0;
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var r = Numbers.Length - 1;
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while (l < r)
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{
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var mid = (l + r) / 2;
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if (Numbers[mid] < target)
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{
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l = mid + 1;
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}
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else
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{
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r = mid;
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}
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}
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return Numbers[l] >= target ? l : l + 1;
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}
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}
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public class Solution {
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public double FindMedianSortedArrays(int[] nums1, int[] nums2)
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{
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var totalNumbers = nums1.Length + nums2.Length;
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var targetOrder1 = (totalNumbers + 1)/2;
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var targetOrder2 = (totalNumbers + 2)/2;
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var range1 = new Range(nums1);
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var range2 = new Range(nums2);
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var number1 = FindMedianSortedArrays(range1, range2, targetOrder1);
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var number2 = targetOrder1 == targetOrder2 ? number1 : FindMedianSortedArrays(range1, range2, targetOrder2);
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return ((double) number1 + number2)/2;
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}
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private int FindMedianSortedArrays(Range range1, Range range2, int targetOrder)
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{
81+
if (range1.Count == 0)
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{
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return range2[targetOrder - 1];
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}
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if (range2.Count == 0)
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{
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return range1[targetOrder - 1];
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}
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var midNumber = range1[(range1.Count - 1)/2];
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var midRanges = new[] { range1.GetSubRange(midNumber, midNumber), range2.GetSubRange(midNumber, midNumber) };
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var leftRanges = new[]
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{
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new Range(range1.Numbers, range1.LeftIndex, midRanges[0].LeftIndex - 1),
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new Range(range2.Numbers, range2.LeftIndex, midRanges[1].LeftIndex - 1)
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};
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var rightRanges = new[]
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{
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new Range(range1.Numbers, midRanges[0].RightIndex + 1, range1.RightIndex),
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new Range(range2.Numbers, midRanges[1].RightIndex + 1, range2.RightIndex)
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};
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var leftCount = leftRanges.Sum(r => r.Count);
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var midCount = midRanges.Sum(r => r.Count);
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var rightCount = rightRanges.Sum(r => r.Count);
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if (leftCount == 0 && rightCount == 0)
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{
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return midNumber;
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}
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if (leftCount >= targetOrder)
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{
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return FindMedianSortedArrays(leftRanges[0], leftRanges[1], targetOrder);
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}
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if (leftCount + midCount >= targetOrder)
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{
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return FindMedianSortedArrays(midRanges[0], midRanges[1], targetOrder - leftCount);
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}
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return FindMedianSortedArrays(rightRanges[0], rightRanges[1], targetOrder - leftCount - midCount);
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}
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}

‎solution/0005.Longest Palindromic Substring/Solution.cs

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public class Solution {
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public string LongestPalindrome(string s) {
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var f = new bool[s.Length];
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var maxLen = 0;
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var index = 0;
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for (var p = 0; p <= 1; ++p)
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{
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for (var l = 1 + p; l <= s.Length; l += 2)
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{
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for (var i = 0; i <= s.Length - l; ++i)
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{
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if (l <= 2)
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{
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f[i] = s[i] == s[i + l - 1];
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}
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else
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{
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f[i] = f[i + 1] && s[i] == s[i + l - 1];
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}
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if (f[i] && l > maxLen)
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{
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maxLen = l;
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index = i;
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}
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}
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}
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}
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return s.Substring(index, maxLen);
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}
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}

‎solution/0006.ZigZag Conversion/Solution.cs

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using System.Collections.Generic;
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using System.Linq;
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public class Solution {
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public string Convert(string s, int numRows) {
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if (numRows == 1) return s;
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if (numRows > s.Length) numRows = s.Length;
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var rows = new List<char>[numRows];
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var i = 0;
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var j = 0;
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var down = true;
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while (i < s.Length)
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{
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if (rows[j] == null)
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{
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rows[j] = new List<char>();
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}
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rows[j].Add(s[i]);
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j = j + (down ? 1 : -1);
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if (j == numRows || j < 0)
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{
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down = !down;
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j = j + (down ? 2 : -2);
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}
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++i;
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}
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return new string(rows.SelectMany(row => row).ToArray());
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}
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}

‎solution/0007.Reverse Integer/Solution.cs

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public class Solution {
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public int Reverse(int x) {
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var negative = x < 0;
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if (negative) x = -x;
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long result = 0;
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while (x > 0)
7+
{
8+
result = (result * 10) + x % 10;
9+
x /= 10;
10+
}
11+
if (negative) result = -result;
12+
if (result > int.MaxValue || result < int.MinValue) result = 0;
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return (int) result;
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}
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}

‎solution/0008.String to Integer (atoi)/Solution.cs

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// https://leetcode.com/problems/string-to-integer-atoi/
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public partial class Solution
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{
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public int MyAtoi(string str)
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{
7+
int i = 0;
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long result = 0;
9+
bool minus = false;
10+
while (i < str.Length && char.IsWhiteSpace(str[i]))
11+
{
12+
++i;
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}
14+
if (i < str.Length)
15+
{
16+
if (str[i] == '+')
17+
{
18+
++i;
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}
20+
else if (str[i] == '-')
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{
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minus = true;
23+
++i;
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}
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}
26+
while (i < str.Length && char.IsDigit(str[i]))
27+
{
28+
result = result * 10 + str[i] - '0';
29+
if (result > int.MaxValue)
30+
{
31+
break;
32+
}
33+
++i;
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}
35+
if (minus) result = -result;
36+
if (result > int.MaxValue)
37+
{
38+
result = int.MaxValue;
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}
40+
if (result < int.MinValue)
41+
{
42+
result = int.MinValue;
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}
44+
return (int)result;
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}
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}

‎solution/0010.Regular Expression Matching/Solution.cs

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public class Solution {
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public bool IsMatch(string s, string p) {
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var f = new bool[s.Length + 1, p.Length + 1];
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f[0, 0] = true;
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for (var i = 0; i <= s.Length; ++i)
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{
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for (var j = 0; j <= p.Length; ++j)
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{
9+
if (i != 0 || j != 0)
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{
11+
if (j == 0)
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{
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f[i, j] = false;
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}
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else if (i == 0)
16+
{
17+
if (p[j - 1] == '*')
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{
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f[i, j] = f[i, j - 2];
20+
}
21+
else
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{
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f[i, j] = false;
24+
}
25+
}
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else
27+
{
28+
if (p[j - 1] == '.')
29+
{
30+
f[i, j] = f[i - 1, j - 1];
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}
32+
else if (p[j - 1] == '*')
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{
34+
f[i, j] = f[i - 1, j] && (s[i - 1] == p[j - 2] || p[j - 2] == '.') || f[i, j - 2];
35+
}
36+
else
37+
{
38+
f[i, j] = f[i - 1, j - 1] && s[i - 1] == p[j - 1];
39+
}
40+
}
41+
}
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}
43+
}
44+
45+
return f[s.Length, p.Length];
46+
}
47+
}

‎solution/0014.Longest Common Prefix/Solution.cs

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using System.Text;
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using System.Linq;
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4+
public class Solution {
5+
public string LongestCommonPrefix(string[] strs) {
6+
if (strs.Length == 0) return string.Empty;
7+
var sb = new StringBuilder();
8+
for (var i = 0; i < strs[0].Length; ++i)
9+
{
10+
var ch = strs[0][i];
11+
if (strs.All(str => str.Length > i && str[i] == ch))
12+
{
13+
sb.Append(ch);
14+
}
15+
else
16+
{
17+
break;
18+
}
19+
}
20+
return sb.ToString();
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}
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}

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