12345的排列和组合

[vic_xx]

写2个函数
1，输出12345的排列
2，由用户输入一个整数（n），n<5,从12345选取n个数的组合...

[blueink_200451]

#include <stdio.h>
#define MAX 10

char used[MAX];
char out[MAX];
int set[MAX] = {1,2,3,4,5};
 
void C(int position, int h, int n, int m)
{
     int i;
     if(position == m)
     {
        for(i=0; i<m; i++)
            printf("%d ", out[i]);
        printf("\n");
        return;
     }
     for(i=h; i<=n-m+position; i++)
        if (!used[i])
        {
            out[position] = set[i];
            used[i]++;
            C(position+1, i+1, n, m);
            used[i]--;
        }
}

int main()
{
	C(0,0,5,5);//第一题

    C(0,0,5,1);//第二题
    C(0,0,5,2);
	C(0,0,5,3);
	C(0,0,5,4);
	C(0,0,5,5);
    return 0;
}

[liyanlin122]

慢慢看

[十八道胡同]

c#和c++是差不多的语法

using System;
using System.Collections.Generic;
using System.Diagnostics;
namespace Test
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = 40;
            int m = 6;
            string[] set = new string[n];
            for (int i = 0; i < n; i++)
            {
                set[i] = i.ToString().PadLeft(2, '0');
            }
            List<string> result;

            GC.Collect();
            Stopwatch watch = new Stopwatch();
            using (new AutoWatch(watch))
            {
                //result = GetCombinationF1(set, m);//n=20 about 130ms;
                //result = GetCombinationF2(set, m); //n=20 about 44ms, n=40 about 6s
                //result = GetCombinationF3(set, m);//n=20 about 16ms n=40 about 2.5s
                result = GetCombinationF4(set, m);//n=20 about 95ms n=40 about 13s
            }
            Console.WriteLine(watch.ElapsedMilliseconds);

            //print output
            foreach (string s in result)
            {
                //Console.WriteLine(s);
            }
        }

        static List<string> GetCombinationF3(string[] data, int count)
        {
            Dictionary<string, int> dic = new Dictionary<string, int>();
            List<string> output = new List<string>();
            for (int i = 0; i < data.Length; i++)
            {
                dic.Add(data[i], i);
            }
            SelectN(dic, data, count, 1, ref output);
            return output;
        }

        static void SelectN(Dictionary<string, int> dd, string[] data, int count, int times, ref List<string> output)
        {
            Dictionary<string, int> dic = new Dictionary<string, int>();
            
            foreach (KeyValuePair<string, int> kv in dd)
            {
                for (int i = kv.Value + 1; i < data.Length; i++)
                {
                    if (times < count - 1)
                    {
                        dic.Add(kv.Key + "\t" + data[i], i);
                    }
                    else
                    {
                        output.Add(kv.Key + "\t" + data[i]);//不考虑输出，将此句注释掉
                    }
                }
            }
            times++;
            if (dic.Count > 0) SelectN(dic, data, count, times,ref output);
        }


        static List<string> GetCombinationF1(string[] set,int m)
        {
            int n = set.Length;
            int min = (0x01 << m) - 1;//00111111
            int max = min << (n - m);//11111100
            int j;
            int k;
            List<string> output = new List<string>();
            string s;

            for (int i = min; i <= max; i++)
            {
                j = 0;
                k = i;
                while (k > 0)
                {
                    j += (int)(k & 0x01);
                    k >>= 1;
                    if (j > m)
                    {
                        break;
                    }
                }
                if (j == m)
                {
                    s = "";
                    k = 0x01;
                    for (int l = n - 1; l >= 0; l--)
                    {
                        if ((k & i) == k)
                        {
                            s+=set[l] + "\t";
                        }
                        k <<= 1;
                    }
                    output.Add(s);
                } 

            }
            return output;
        }


        static List<string> GetCombinationF2(string[] strArray, int selectCount)
        {
            int totalCount = strArray.Length;
            int[] currentSelect = new int[selectCount];
            int last = selectCount - 1;
            List<string> output = new List<string>();
            string s;

            //付初始值
            for (int i = 0; i < selectCount; i++)
                currentSelect[i] = i;

            while (true)
            {
                s = "";
                //输出部分,生成的时候从0计数,所以输出的时候+1
                for (int i = 0; i < selectCount; i++)
                {
                    s += strArray[currentSelect[i]]+"\t";
                }
                output.Add(s);

                //如果不进位
                if (currentSelect[last] < totalCount - 1)
                    currentSelect[last]++;
                else
                {
                    //进位部分
                    int position = last;

                    while (position > 0 && currentSelect[position - 1] == currentSelect[position] - 1)
                        position--;

                    if (position == 0)
                        break ;

                    currentSelect[position - 1]++;

                    for (int i = position; i < selectCount; i++)
                        currentSelect[i] = currentSelect[i - 1] + 1;
                }
            }
            return output;
        }

        static List<string> GetCombinationF4(string[] data, int count)
        {
            List<string> output = new List<string>();
            int len = data.Length;
            string start = "1".PadRight(count, '1').PadRight(len, '0');
            string s;
            while (start != string.Empty)
            {
                s = "";
                for (int i = 0; i < len; i++)
                    if (start[i] == '1') s+=data[i] + "\t";
                output.Add(s);
                start = GetNext(start);
            }
            return output;

        }

        static string GetNext(string str)
        {
            string next = string.Empty;
            int pos = str.IndexOf("10");
            if (pos < 0) return next;
            else if (pos == 0) return "01" + str.Substring(2);
            else
            {
                int len = str.Length;
                next = str.Substring(0, pos).Replace("0", "").PadRight(pos, '0') + "01";
                if (pos < len - 2) next += str.Substring(pos + 2);
            }
            return next;
        }


        public sealed class AutoWatch : IDisposable
        {
            private Stopwatch watch;

            public AutoWatch(Stopwatch watch)
            {
                this.watch = watch;
                watch.Start();
            }

            void IDisposable.Dispose()
            {
                watch.Stop();
            }
        }   

    }
}

[ithiker]

[Quote=引用 1 楼 blueink_200451 的回复:]
C/C++ code

#include <stdio.h>
#define MAX 10

char used[MAX];
char out[MAX];
int set[MAX] = {1,2,3,4,5};

void C(int position, int h, int n, int m)
{
int i;
if(position == m)
……
[/Quote]
5个数的排列好像没有...

[yuandei]

#include <stdio.h>
#define MAX 10

char used[MAX];
char out[MAX];
int set[MAX] = {1,2,3,4,5};

void C(int position, int h, int n, int m)
{
int i;
if(position == m)
{
for(i=0; i<m; i++)
printf("%d ", out[i]);
printf("\n");
return;
}
for(i=h; i<=n-m+position; i++)
if (!used[i])
{
out[position] = set[i];
used[i]++;
C(position+1, i+1, n, m);
used[i]--;
}
}

int main()
{
C(0,0,5,5);//第一题

C(0,0,5,1);//第二题
C(0,0,5,2);
C(0,0,5,3);
C(0,0,5,4);
C(0,0,5,5);
return 0;

[vic_xx]

[Quote=引用 1 楼 blueink_200451 的回复:]
C/C++ code

#include <stdio.h>
#define MAX 10

char used[MAX];
char out[MAX];
int set[MAX] = {1,2,3,4,5};

void C(int position, int h, int n, int m)
{
int i;
if(position == m)
……
[/Quote]

不是很懂哦，能否详细解释一下啊！