/*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++;
}
}
}
}
「機能が実装されていない」とは宿題を意味するため、完全なコードは記載しません。はい、再帰を使用できます。その文字を取り除くたびに、文字列中の文字を繰り返し処理して、呼び出し中にまだ使用されていない文字を渡すことができます。合理的な関数シグネチャは 'void f(std :: vector&results、const std :: string&unused_chars、const std :: string&prefix_so_far =" ")'です。 'f'が' unused_chars'を空にすると 'results_'に' prefix_so_far'を追加することができます。 –
組み合わせは順列とは異なります(あなたの例)。組み合わせでは、要素の順序は重要ではなく、順序は順列で重要です。 – rendon
すべての組み合わせをベクトルにプッシュして並べ替えます。 –