递归输出全排列和全组合
// 输出全排列
// author: kennie
#include<iostream>
template<typename T>
void swap(T *, T *);
template<typename T>
void printArr(T [], int len);
template<typename T>
void permutation(T [], int, int, int);
template<typename T>
void swap( T *a, T *b )
{
T tmp;
tmp = *a;
*a = *b;
*b = tmp;
}
template<typename T>
void printArr( T arr[], int len )
{
for ( int i = 0; i < len; i++ )
{
std::cout << arr[i] << "\t" ;
}
std::cout << std::endl;
}
template<typename T>
void permutation( T arr[], int len, int startIndex, int endIndex ) // 递归求解全排列
{
if ( startIndex > endIndex ) // 递归出口
{
printArr( arr, len );
}
else
{
for ( int j = startIndex; j <= endIndex; j++ ) // 依次交换数组元素与数组首元素
{
swap( &arr[j], &arr[startIndex]);
permutation( arr, len, startIndex+1, endIndex ); // 除去当前元素，剩余元素的全排列
swap( &arr[j], &arr[startIndex]);
}
}
}
int main()
{
// test
int intArr [] = { 1, 2, 3 };
int len = sizeof ( intArr ) / sizeof ( int );
std::cout << "test int" << std::endl;
permutation( intArr, len, 0, len-1 );
std::cout << std::endl;
char charArr[] = { 'a', 'b', 'c', 'd' };
int len2 = sizeof ( charArr ) / sizeof( char );
std::cout << "test char" << std::endl;
permutation( charArr, len2, 0, len2-1 );
std::cout << std::endl;
return 0;
}
// main output as follow:
test int 1 2 3 1 3 2 2 1 3 2 3 1 3 2 1 3 1 2 test char a b c d a b d c a c b d a c d b a d c b a d b c b a c d b a d c b c a d b c d a b d c a b d a c c b a d c b d a c a b d c a d b c d a b c d b a d b c a d b a c d c b a d c a b d a c b d a b c
// 输出全组合
#include<stdio.h>
#include<stdlib.h>
#include<iostream>
#include<vector>
using namespace std;
void recursive_combination(char* str, int num, vector<char> & result) // 从n个字符中取m个的组合
{
if ( num == 0 )
{
int length = result.size();
for ( int i = 0; i < length; i++ )
{
cout << result[i];
}
cout << endl;
return;
}
if ( *str == '\0' )
{
return;
}
result.push_back( *str ); // 取当前字符
recursive_combination( str+1, num-1, result );
result.pop_back(); // 不取当前字符
recursive_combination( str+1, num, result );
}
void combination( char* str, int len )
{
if ( str == NULL )
{
return;
}
vector<char> result;
for ( int i = 1; i <= len; i++ ) // 每一个组合长度
{
recursive_combination(str, i, result);
}
}
int main()
{
char str[] = {"abcd"};
int len = sizeof (str) / sizeof (char);
cout << "src" << str << endl;
cout << "output all combination: " << endl;
combination(str, len);
return 0;
}
// main output as follow:
src: abcd output all combination: a b c d ab ac ad bc bd cd abc abd acd bcd abcd