我有一个数组，用户可以插入一个字符串。
我有这个代码：
int main(){
char anagrama[13];
cin >> anagrama;
for(int j = 0; j < strlen(anagrama); j++){
cout << anagrama[j];
for(int k = 0; k < strlen(anagrama); k++){
if(j != k)
cout << anagrama[k];
}
cout << endl;
}
}
问题是我需要按排序顺序排列字符串的所有排列。
例如，如果用户写：
abcabc
acb
bac
bca
cab
cba
我的代码没有显示所有排列，并且没有排序
你能帮我吗？
我需要在尚未实现功能的情况下进行实现。
我想用递归函数，但我不知道如何。
这是一个例子： http://www.disfrutalasmatematicas.com/combinatoria/combinaciones-permutaciones-calculadora.html无重复且已排序
std::next_permutationstd::next_permutationcin>>anagrama;
int len = strlen(anagrama);
sort(anagrama, anagrama+len);
do {
cout << anagrama << endl;
} while (next_permutation(anagrama, anagrama+len));
这是 ideone 上的演示。
如果您必须自己实现排列，您可以借用next_permutation
的源代码，或者选择一种更简单的递归实现排列算法的方法。
#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
void permute(string select, string remain){
if(remain == ""){
cout << select << endl;
return;
}
for(int i=0;remain[i];++i){
string wk(remain);
permute(select + remain[i], wk.erase(i, 1));
}
}
int main(){
string anagrama;
cout << "input character set >";
cin >> anagrama;
sort(anagrama.begin(), anagrama.end());
permute("", anagrama);
}
另一个版本
#include <iostream>
#include <string>
#include <vector>
#include <iterator>
#include <algorithm>
using namespace std;
void permute(string& list, int level, vector<string>& v){
if(level == list.size()){
v.push_back(list);
return;
}
for(int i=level;list[i];++i){
swap(list[level], list[i]);
permute(list, level + 1, v);
swap(list[level], list[i]);
}
}
int main(){
string anagrama;
vector<string> v;
cout << "input character set >";
cin >> anagrama;
permute(anagrama, 0, v);
sort(v.begin(), v.end());
copy(v.begin(), v.end(), ostream_iterator<string>(cout, "\n"));
}
@alexander 该程序的输出与您要求的顺序完全相同：
HERE，是生成给定数组的所有组合/排列的最简单代码，不包含一些特殊库（仅包含 iostream.h 和 string），并且不使用比平常更特殊的命名空间（仅 namespace std被使用）。
void shuffle_string_algo( string ark )
{
//generating multi-dimentional array:
char** alpha = new char*[ark.length()];
for (int i = 0; i < ark.length(); i++)
alpha[i] = new char[ark.length()];
//populating given string combinations over multi-dimentional array
for (int i = 0; i < ark.length(); i++)
for (int j = 0; j < ark.length(); j++)
for (int n = 0; n < ark.length(); n++)
if( (j+n) <= 2 * (ark.length() -1) )
if( i == j-n)
alpha[i][j] = ark[n];
else if( (i-n)== j)
alpha[i][j] = ark[ ark.length() - n];
if(ark.length()>=2)
{
for(int i=0; i<ark.length() ; i++)
{
char* shuffle_this_also = new char(ark.length());
int j=0;
//storing first digit in golobal array ma
ma[v] = alpha[i][j];
//getting the remaning string
for (; j < ark.length(); j++)
if( (j+1)<ark.length())
shuffle_this_also[j] = alpha[i][j+1];
else
break;
shuffle_this_also[j]='\0';
//converting to string
string send_this(shuffle_this_also);
//checking if further combinations exist or not
if(send_this.length()>=2)
{
//review the logic to get the working idea of v++ and v--
v++;
shuffle_string_algo( send_this);
v--;
}
else
{
//if, further combinations are not possiable print these combinations
ma[v] = alpha[i][0];
ma[++v] = alpha[i][1];
ma[++v] = '\0';
v=v-2;
string disply(ma);
cout<<++permutaioning<<":\t"<<disply<<endl;
}
}
}
}
和主要：
int main()
{
string a;
int ch;
do
{
system("CLS");
cout<<"PERMUNATING BY ARK's ALGORITH"<<endl;
cout<<"Enter string: ";
fflush(stdin);
getline(cin, a);
ma = new char[a.length()];
shuffle_string_algo(a);
cout<<"Do you want another Permutation?? (1/0): ";
cin>>ch;
} while (ch!=0);
return 0;
}
希望！它对你有帮助！如果您在理解逻辑时遇到问题，请在下面发表评论，我将进行编辑。
/*Think of this as a tree. The depth of the tree is same as the length of string.
In this code, I am starting from root node " " with level -1. It has as many children as the characters in string. From there onwards, I am pushing all the string characters in stack.
Algo is like this:
1. Put root node in stack.
2. Loop till stack is empty
2.a If backtracking
2.a.1 loop from last of the string character to present depth or level and reconfigure datastruture.
2.b Enter the present char from stack into output char
2.c If this is leaf node, print output and continue with backtracking on.
2.d Else find all the neighbors or children of this node and put it them on stack. */
class StringEnumerator
{
char* m_string;
int m_length;
int m_nextItr;
public:
StringEnumerator(char* str, int length): m_string(new char[length + 1]), m_length(length) , m_Complete(m_length, false)
{
memcpy(m_string, str, length);
m_string[length] = 0;
}
StringEnumerator(const char* str, int length): m_string(new char[length + 1]), m_length(length) , m_Complete(m_length, false)
{
memcpy(m_string, str, length);
m_string[length] = 0;
}
~StringEnumerator()
{
delete []m_string;
}
void Enumerate();
};
const int MAX_STR_LEN = 1024;
const int BEGIN_CHAR = 0;
struct StackElem
{
char Elem;
int Level;
StackElem(): Level(0), Elem(0){}
StackElem(char elem, int level): Elem(elem), Level(level){}
};
struct CharNode
{
int Max;
int Curr;
int Itr;
CharNode(int max = 0): Max(max), Curr(0), Itr(0){}
bool IsAvailable(){return (Max > Curr);}
void Increase()
{
if(Curr < Max)
Curr++;
}
void Decrease()
{
if(Curr > 0)
Curr--;
}
void PrepareItr()
{
Itr = Curr;
}
};
void StringEnumerator::Enumerate()
{
stack<StackElem> CStack;
int count = 0;
CStack.push(StackElem(BEGIN_CHAR,-1));
char answerStr[MAX_STR_LEN];
memset(answerStr, 0, MAX_STR_LEN);
bool forwardPath = true;
typedef std::map<char, CharNode> CharMap;
typedef CharMap::iterator CharItr;
typedef std::pair<char, CharNode> CharPair;
CharMap mCharMap;
CharItr itr;
//Prepare Char Map
for(int i = 0; i < m_length; i++)
{
itr = mCharMap.find(m_string[i]);
if(itr != mCharMap.end())
{
itr->second.Max++;
}
else
{
mCharMap.insert(CharPair(m_string[i], CharNode(1)));
}
}
while(CStack.size() > 0)
{
StackElem elem = CStack.top();
CStack.pop();
if(elem.Level != -1) // No root node
{
int currl = m_length - 1;
if(!forwardPath)
{
while(currl >= elem.Level)
{
itr = mCharMap.find(answerStr[currl]);
if((itr != mCharMap.end()))
{
itr->second.Decrease();
}
currl--;
}
forwardPath = true;
}
answerStr[elem.Level] = elem.Elem;
itr = mCharMap.find(elem.Elem);
if((itr != mCharMap.end()))
{
itr->second.Increase();
}
}
//If leaf node
if(elem.Level == (m_length - 1))
{
count++;
cout<<count<<endl;
cout<<answerStr<<endl;
forwardPath = false;
continue;
}
itr = mCharMap.begin();
while(itr != mCharMap.end())
{
itr->second.PrepareItr();
itr++;
}
//Find neighbors of this elem
for(int i = 0; i < m_length; i++)
{
itr = mCharMap.find(m_string[i]);
if(/*(itr != mCharMap.end()) &&*/ (itr->second.Itr < itr->second.Max))
{
CStack.push(StackElem(m_string[i], elem.Level + 1));
itr->second.Itr++;
}
}
}
}
我写的一个函数甚至没有实现任何模板和容器。实际上它最初是用 C 编写的，但已转换为 C++。
容易理解，但效率较差，而且它的输出就是你想要的，排序好的。
#include <iostream>
#define N 4
using namespace std;
char ch[] = "abcd";
int func(int n) {
int i,j;
char temp;
if(n==0) {
for(j=N-1;j>=0;j--)
cout<<ch[j];
cout<<endl;
return 0;
}
for(i=0;i<n;i++){
temp = ch[i];
for(j=i+1;j<n;j++)
ch[j-1] = ch[j];
ch[n-1] = temp;
//shift
func(n-1);
for(j=n-1;j>i;j--)
ch[j] = ch[j-1];
ch[i] = temp;
//and shift back agian
}
return 1;
}
int main(void)
{
func(N);
return 0;
}
如果您有 std::vector 字符串，那么您可以按如下方式“排列”向量项。
C++14 代码
#include <iostream>
#include <algorithm>
#include <iostream>
#include <string>
#include <vector>
#include <boost/algorithm/string/join.hpp>
using namespace std;
int main() {
// your code goes here
std::vector<std::string> s;
s.push_back("abc");
s.push_back("def");
s.push_back("ghi");
std::sort(s.begin(), s.end());
do
{
std::cout << boost::algorithm::join(s,"_") << std::endl ;
} while(std::next_permutation(s.begin(), s.end()));
return 0;
}
输出：
abc_def_ghi
abc_ghi_def
def_abc_ghi
def_ghi_abc
ghi_abc_def
ghi_def_abc
正如其他评论中提到的，您应该使用
std::next_permutationstd::generatorhttps://godbolt.org/z/Ynrheo9TK
template<typename Container>
std::generator<Container> get_permutations(Container c)
{
std::sort(std::begin(c), std::end(c));
do {
co_yield c;
} while(std::next_permutation(std::begin(c), std::end(c)));
}