From 8938c3447d88e31f77f20553ed185fc8e64c9ac8 Mon Sep 17 00:00:00 2001 From: chai Date: Tue, 22 Jun 2021 14:58:53 +0800 Subject: +misc --- Assets/Algorithms/Sorting/Sorting.cs | 159 ++++++++++++++++++++++++++++++ Assets/Algorithms/Sorting/Sorting.cs.meta | 11 +++ 2 files changed, 170 insertions(+) create mode 100644 Assets/Algorithms/Sorting/Sorting.cs create mode 100644 Assets/Algorithms/Sorting/Sorting.cs.meta (limited to 'Assets/Algorithms/Sorting') diff --git a/Assets/Algorithms/Sorting/Sorting.cs b/Assets/Algorithms/Sorting/Sorting.cs new file mode 100644 index 0000000..292f7eb --- /dev/null +++ b/Assets/Algorithms/Sorting/Sorting.cs @@ -0,0 +1,159 @@ +using System; +using System.Collections; +using System.Collections.Generic; +using AlgorithmCollection; + +//https://zh.wikipedia.org/wiki/%E6%8E%92%E5%BA%8F%E7%AE%97%E6%B3%95 +namespace AlgorithmCollection.Sorting +{ + + // 排序主要关注稳定性和效率 + // *稳定性，相同值的元素相对位置在排序前后是否改变 + // *效率，时间复杂度和空间复杂度 + public static class SortingHelper + { + + // 选择合适的算法排序 + public static void Sort(T[] data, bool bDescent = false, bool bStable = false) where T : IComparable, IEquatable + { + int n = data.Length; + } + + #region 归并排序 + // 归并排序 | 稳定 | 分治法 + // T(n) = O(nlogn) 渐进最优 + // S(n) = O(n) 需要大小为n的额外空间 + public static void MergeSort(T[] data, bool descent = false) where T : IComparable, IEquatable + { + T[] temp = new T[data.Length];// 需要额外的临时空间 + _MergeSort(data, 0, data.Length - 1, descent, temp); + } + + // 归并排序，非递归 + public static void MergeSort_NoneRecursion(T[] data, bool descent = false) where T : IComparable, IEquatable + { + T[] temp = new T[data.Length];// 需要额外的临时空间 + int s = 1; + int n = data.Length; + for(int seg = 1; seg < n; seg += seg) //步长1,2,4,8... + { + for(int start = 0; start < n; start += seg * 2) + { + int left = start, right = Algorithms.Min(start + seg * 2 - 1, n - 1); + int mid = Algorithms.Min(start + seg - 1, n - 1); + _Merge(data, left, mid, right, descent, temp); + _CopyTo(temp, data, left, right); + } + } + } + + private static void _MergeSort(T[] data, int left, int right, bool descent, T[] temp) where T : IComparable, IEquatable + { + // 这是一个O(logn)的分治算法，对于每此分治，会有一个O(n)的合并算法，所以归并排序复杂度是O(nlogn) + if (left < right) + { + int middle = (left + right) / 2; + _MergeSort(data, left, middle, descent, temp); + _MergeSort(data, middle + 1, right, descent, temp); + _Merge(data, left, middle, right, descent, temp);// 把left~right部分合并到temp中 + _CopyTo(temp, data, left, right); // 把合并后的temp部分复制回去 + } + } + + private static T[] _Merge(T[]data, int left, int middle, int right, bool descent, T[] temp) where T : IComparable, IEquatable + { + // 这是一个O(n)的合并算法 + int l = left, r = middle + 1; + int i = 0; + while(l <= middle || r <= right) + { + if(l > middle) + { + temp[i++] = data[r++]; + continue; + } + if(r > right) + { + temp[i++] = data[l++]; + continue; + } + if (descent && data[l].CompareTo(data[r]) > 0 || !descent && data[l].CompareTo(data[r]) < 0) + { + temp[i++] = data[l]; + l++; + } + else + { + temp[i++] = data[r]; + r++; + } + } + return temp; + } + + private static void _CopyTo(T[] src, T[] dst, int from, int to) + { + for (int i = from; i <= to; ++i) + dst[i] = src[i - from]; + } + + #endregion + + #region 快速排序 + // 快速排序 | 不稳定 | 原地排序 | 分治法 + // 平均T(n)=O(nlogn)，最坏T(n)=O(n²) + // S(n)=O(1) + public static void QuickSort(T[] data, bool descent = false) where T : IComparable, IEquatable + { + _QuickSort(data, descent, 0, data.Length - 1); + } + private static void _QuickSort(T[] data, bool descent, int start, int end) where T : IComparable, IEquatable + { + if(start < end) + { + int p = _Partion(data, descent, start, end); + _QuickSort(data, descent, start, p - 1); + _QuickSort(data, descent, p + 1, end); + } + } + private static int _Partion(T[] data, bool descent, int start, int end) where T : IComparable + { + T v = data[start]; + int i = start; + int j = end + 1; + while(true) + { + while ((descent && data[++i].CompareTo(v) >= 0 + || !descent && data[++i].CompareTo(v) <= 0) && i < end) ; + while ((descent && data[--j].CompareTo(v) <= 0 + || !descent && data[--j].CompareTo(v) >= 0) && j > start) ; + if (i >= j) + break; + Algorithms.Swap(ref data, i, j); + } + Algorithms.Swap(ref data, start, j); + return j; + } + #endregion + + // 冒泡排序，稳定 + // O(n²) + public static void BubbleSort(T[] data, bool descent = false) where T : IComparable, IEquatable + { + int n = data.Length; + for(int i = 0; i < n; ++i) + { + for(int j = 0; j < n - i - 1; ++j) + { + if (descent && data[j].CompareTo(data[j + 1]) < 0 + || !descent && data[j].CompareTo(data[j + 1]) > 0) + { + Algorithms.Swap(ref data, j, j + 1); + } + } + } + } + + } + +} \ No newline at end of file diff --git a/Assets/Algorithms/Sorting/Sorting.cs.meta b/Assets/Algorithms/Sorting/Sorting.cs.meta new file mode 100644 index 0000000..5958b22 --- /dev/null +++ b/Assets/Algorithms/Sorting/Sorting.cs.meta @@ -0,0 +1,11 @@ +fileFormatVersion: 2 +guid: 43b3b96427109e2459a379a1f36de857 +MonoImporter: + externalObjects: {} + serializedVersion: 2 + defaultReferences: [] + executionOrder: 0 + icon: {instanceID: 0} + userData: + assetBundleName: + assetBundleVariant: -- cgit v1.1-26-g67d0