public static int RemoveDuplicates(ref int[] array)
{
    int size = array.Length;

    // if 0 or 1, return 0 or 1:
    if (size  < 2) {
        return size;
    }

    int current = 0;
    for (int candidate = 1; candidate < size; ++candidate) {
        if (array[current] != array[candidate]) {
            array[++current] = array[candidate];
        }
    }

    // index to count conversion:
    return ++current;
}

——这是面试中每次都会问的问题。现在我完成了它的编码。

static void Main(string[] args)
{    
            int[] array = new int[] { 4, 8, 4, 1, 1, 4, 8 };            
            int numDups = 0, prevIndex = 0;

            for (int i = 0; i < array.Length; i++)
            {
                bool foundDup = false;
                for (int j = 0; j < i; j++)
                {
                    if (array[i] == array[j])
                    {
                        foundDup = true;
                        numDups++; // Increment means Count for Duplicate found in array.
                        break;
                    }                    
                }

                if (foundDup == false)
                {
                    array[prevIndex] = array[i];
                    prevIndex++;
                }
            }

            // Just Duplicate records replce by zero.
            for (int k = 1; k <= numDups; k++)
            {               
                array[array.Length - k] = '\0';             
            }


            Console.WriteLine("Console program for Remove duplicates from array.");
            Console.Read();
        }

下面经过测试和工作的代码将从数组中删除重复项。你必须包括系统。集合名称空间。

string[] sArray = {"a", "b", "b", "c", "c", "d", "e", "f", "f"};
var sList = new ArrayList();

for (int i = 0; i < sArray.Length; i++) {
    if (sList.Contains(sArray[i]) == false) {
        sList.Add(sArray[i]);
    }
}

var sNew = sList.ToArray();

for (int i = 0; i < sNew.Length; i++) {
    Console.Write(sNew[i]);
}

如果你愿意，你可以把它打包成一个函数。

public static int RemoveDuplicates(ref int[] array)
{
    int size = array.Length;

    // if 0 or 1, return 0 or 1:
    if (size  < 2) {
        return size;
    }

    int current = 0;
    for (int candidate = 1; candidate < size; ++candidate) {
        if (array[current] != array[candidate]) {
            array[++current] = array[candidate];
        }
    }

    // index to count conversion:
    return ++current;
}

最好的方法是什么?很难说，HashSet方法看起来很快， 但是(取决于数据)使用排序算法(CountSort ?) 可以快得多。

using System;
using System.Collections.Generic;
using System.Linq;
class Program
{
    static void Main()
    {
        Random r = new Random(0); int[] a, b = new int[1000000];
        for (int i = b.Length - 1; i >= 0; i--) b[i] = r.Next(b.Length);
        a = new int[b.Length]; Array.Copy(b, a, b.Length);
        a = dedup0(a); Console.WriteLine(a.Length);
        a = new int[b.Length]; Array.Copy(b, a, b.Length);
        var w = System.Diagnostics.Stopwatch.StartNew();
        a = dedup0(a); Console.WriteLine(w.Elapsed); Console.Read();
    }

    static int[] dedup0(int[] a)  // 48 ms  
    {
        return new HashSet<int>(a).ToArray();
    }

    static int[] dedup1(int[] a)  // 68 ms
    {
        Array.Sort(a); int i = 0, j = 1, k = a.Length; if (k < 2) return a;
        while (j < k) if (a[i] == a[j]) j++; else a[++i] = a[j++];
        Array.Resize(ref a, i + 1); return a;
    }

    static int[] dedup2(int[] a)  //  8 ms
    {
        var b = new byte[a.Length]; int c = 0;
        for (int i = 0; i < a.Length; i++) 
            if (b[a[i]] == 0) { b[a[i]] = 1; c++; }
        a = new int[c];
        for (int j = 0, i = 0; i < b.Length; i++) if (b[i] > 0) a[j++] = i;
        return a;
    }
}

几乎没有分支。怎么做?调试模式，步进(F11)与一个小数组:{1,3,1,1,0}

    static int[] dedupf(int[] a)  //  4 ms
    {
        if (a.Length < 2) return a;
        var b = new byte[a.Length]; int c = 0, bi, ai, i, j;
        for (i = 0; i < a.Length; i++)
        { ai = a[i]; bi = 1 ^ b[ai]; b[ai] |= (byte)bi; c += bi; }
        a = new int[c]; i = 0; while (b[i] == 0) i++; a[0] = i++;
        for (j = 0; i < b.Length; i++) a[j += bi = b[i]] += bi * i; return a;
    }

有两个嵌套循环的解决方案可能需要一些时间， 特别是对于较大的数组。

    static int[] dedup(int[] a)
    {
        int i, j, k = a.Length - 1;
        for (i = 0; i < k; i++)
            for (j = i + 1; j <= k; j++) if (a[i] == a[j]) a[j--] = a[k--];
        Array.Resize(ref a, k + 1); return a;
    }

这段代码从数组中100%删除重复值[因为我使用了一个[I]].....您可以将其转换为任何OO语言.....：）

for(int i=0;i<size;i++)
{
    for(int j=i+1;j<size;j++)
    {
        if(a[i] == a[j])
        {
            for(int k=j;k<size;k++)
            {
                 a[k]=a[k+1];
            }
            j--;
            size--;
        }
    }

}