用C＃在int数组中找到min值

如何用c＃在int中找到最小值

Answer 1

使用LINQ：

int min = theArray.Min(); 

请注意，如果没有任何元素，这将会出错; 首先检查.Length （或者，将项目设置为int? ,但这会增加开销）。

如果您没有可用的LINQ，那么可能：

 public static int Min(int[] arr) { switch (arr.Length) { case 0: throw new InvalidOperationException(); case 1: return arr[0]; case 2: return Math.Min(arr[0], arr[1]); default: int min = arr[0]; for (int i = 1; i < arr.Length; i++) { if (arr[i] < min) min = arr[i]; } return min; } } 

Answer 2

我写下来比较我对@Marc Gravell所说的内容，我告诉我的方式在我的PC上快一点，而linq是最慢的方式，另外如果你改变了函数的位置（在代码中）你将永远获得一个使用if的版本可以获得更好的性能

  static void Main(string[] args) { Dictionary> dic = new Dictionary>(); dic["First"] = new List(); dic["Second"] = new List(); dic["Third"] = new List(); for (int i = 0; i < 500; i++) { int[] array = GetRandomArray(); Stopwatch stopWacth = new Stopwatch(); stopWacth.Restart(); int n1 = FindMin(array); stopWacth.Stop(); long firstTicks = stopWacth.ElapsedTicks; dic["First"].Add(firstTicks); stopWacth.Restart(); int n2 = AnotherFindMin(array); stopWacth.Stop(); long secondTick = stopWacth.ElapsedTicks; dic["Second"].Add(secondTick); stopWacth.Restart(); int n3 = array.Min(); stopWacth.Stop(); long thirdTick = stopWacth.ElapsedTicks; dic["Third"].Add(thirdTick); Console.WriteLine("first tick : {0}, second tick {1}, third tick {2} ", firstTicks, secondTick, thirdTick); } Console.WriteLine("first tick : {0}, second tick {1}, third tick {2} ", dic["First"].Average(), dic["Second"].Average(), dic["Third"].Average()); Console.ReadLine(); } public static int[] GetRandomArray() { int[] retVal = new int[1000000]; Random r = new Random(); for (int i = 0; i < 1000000; i++) { retVal[i] = r.Next(1000000000); } return retVal; } public static int FindMin(int[] arr) { switch (arr.Length) { case 0: throw new InvalidOperationException(); case 1: return arr[0]; case 2: return Math.Min(arr[0], arr[1]); default: int min = arr[0]; for (int i = 1; i < arr.Length; i++) { if (arr[i] < min) min = arr[i]; } return min; } } public static int AnotherFindMin(int[] arr) { if (arr.Length > 0) { int min = arr[0]; for (int i = 1; i < arr.Length; i++) { if (arr[i] < min) min = arr[i]; } return min; } else { throw new InvalidOperationException(); } } } // revised test by Marc (see comments discussion) static class Test { static void Main(string[] args) { Dictionary> dic = new Dictionary>(); dic["First"] = new List(); dic["Second"] = new List(); dic["Third"] = new List(); const int OUTER_LOOP = 500, INNER_LOOP = 500000; for (int arrSize = 1; arrSize <= 3; arrSize++) { for (int i = 0; i < OUTER_LOOP; i++) { int[] array = GetRandomArray(arrSize); Stopwatch stopWacth = Stopwatch.StartNew(); for (int j = 0; j < INNER_LOOP; j++) { int n1 = FindMin(array); } stopWacth.Stop(); long firstTicks = stopWacth.ElapsedTicks; dic["First"].Add(firstTicks); stopWacth = Stopwatch.StartNew(); for (int j = 0; j < INNER_LOOP; j++) { int n2 = AnotherFindMin(array); } stopWacth.Stop(); long secondTick = stopWacth.ElapsedTicks; dic["Second"].Add(secondTick); stopWacth = Stopwatch.StartNew(); for (int j = 0; j < INNER_LOOP; j++) { int n3 = array.Min(); } stopWacth.Stop(); long thirdTick = stopWacth.ElapsedTicks; dic["Third"].Add(thirdTick); //Console.WriteLine("{3}: switch : {0}, 0-check {1}, Enumerable.Min {2} ", firstTicks, secondTick, thirdTick, arrSize); } Console.WriteLine("{3}: switch : {0}, 0-check {1}, Enumerable.Min {2} ", dic["First"].Average(), dic["Second"].Average(), dic["Third"].Average(), arrSize); } Console.WriteLine("Done"); Console.ReadLine(); } public static int[] GetRandomArray(int size) { int[] retVal = new int[size]; Random r = new Random(); for (int i = 0; i < retVal.Length; i++) { retVal[i] = r.Next(1000000000); } return retVal; } public static int FindMin(int[] arr) { switch (arr.Length) { case 0: throw new InvalidOperationException(); case 1: return arr[0]; case 2: return arr[0] < arr[1] ? arr[0] : arr[1]; default: int min = arr[0]; for (int i = 1; i < arr.Length; i++) { if (arr[i] < min) min = arr[i]; } return min; } } public static int AnotherFindMin(int[] arr) { if (arr.Length > 0) { int min = arr[0]; for (int i = 1; i < arr.Length; i++) { if (arr[i] < min) min = arr[i]; } return min; } else { throw new InvalidOperationException(); } } }