题目：
一个数组A[1..n]来实现两个栈，使得两个栈中的元素总和不到n时，两个都不会发生上溯。
思路（1）：
创建一个数组，分别从两边开始，依次往中间走。
思路（2）：
创建一个数组，一个走奇数位，一个走偶数位。
//奇偶方式
#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
using namespace std;
template<class T>
class TwoStack
{
public:
TwoStack(int size)
:_top1(-1), _top2(-1), _len(size)
{
_arr = new T[size];
}
~TwoStack()
{
if (_arr)
{
delete[] _arr;
}
}
void Push(int index, int data);
T Pop(int index);
bool IsEmpty(int index);
void Disp();
T Top(int index);
private:
int _top1;
int _top2;
int _len;
T* _arr;
};
template<class T>
void TwoStack<T>::Push(int index, int data)
{
//if (_len % 2 == 0)
//{
//if (_top1>_len-2 || _top2>=_len-1)
//{
//cout << "overflow" << endl;
//return;
//}
//}
//else
//{
//if (_top1 >_len || _top2 >= _len - 2)
//{
//cout << "overflow" << endl;
//return;
//}
//}
int flag = _len % 2;
if (index == 0)
{
if (flag == 0)
{
if (_top1 >= _len - 2)
{
cout << "Stack1 overflow" << endl;
return;
}
}
if (flag == 1)
{
if (_top1 >= _len - 1)
{
cout << "overflow" << endl;
return;
}
}
////////////////////////////
if (_top1 == -1)
{
_top1 = 0;
_arr[_top1] = data;
}
else
{
_top1+=2;
_arr[_top1] = data;
}
}
/////////////////////////////////////////////////////////
else
{
if (flag == 0)
{
if (_top2 >= _len - 2)
{
cout << "Stack2 overflow" << endl;
return;
}
}
if (flag == 1)
{
if (_top2 >= _len - 1)
{
cout << "overflow" << endl;
return;
}
}
///////////////
if (_top2 == -1)
{
_top2 = 1;
_arr[_top2] = data;
}
else
{
_top2+=2;
_arr[_top2] = data;
}
}
}
template<class T>
T TwoStack<T>::Pop(int index)
{
int ret;
if (index == 0)
{
if (_top1 < 0)
{
cout << "Stack1 is null" << endl;
return -1;
}
else
{
ret = _arr[_top1];
_top1-=2;
}
}
else
{
if (_top2 <1)
{
cout << "Stack2 is null" << endl;
return -1;
}
else
{
ret = _arr[_top2];
_top2-=2;
}
}
return ret;
}
template<class T>
bool TwoStack<T>::IsEmpty(int index)
{
if (index == 0 && _top1 < 0)
return true;
if (index == 1 && _top2 < 0)
return true;
return false;
}
template<class T>
void TwoStack<T>::Disp()
{
{
for (int i = 0; i < _len; i++)
{
cout << _arr[i] << " ";
}
}
}
template<class T>
T TwoStack<T>::Top(int index)
{
if (0 == index && _top1 >= 0)
{
return _arr[_top1];
}
if (1 == index && _top2 >=1)
{
return _arr[_top2];
}
cout << "NO TOP" << endl;
exit(0);
}
void test1()
{
TwoStack<int>s(10);
s.Push(0, 1);
s.Push(0, 2);
s.Push(0, 3);
s.Push(0, 4);
s.Push(0, 5);
//s.Push(0, 5);
s.Push(1, 6);
s.Push(1, 7);
s.Push(1, 8);
s.Push(1, 9);
s.Push(1, 10);
//s.Push(1, 10);
//cout << s.Top(1);
//cout<<s.IsEmpty(0);
s.Disp();
}
void test2()
{
TwoStack<int>s(10);
s.Push(0, 1);
s.Push(0, 2);
s.Push(0, 3);
s.Push(0, 4);
s.Push(0, 5);
s.Push(1, 6);
s.Push(1, 7);
s.Push(1, 8);
s.Push(1, 9);
s.Push(1, 10);
cout << s.Pop(0)<<" ";
cout << s.Pop(0) << " ";
cout << s.Pop(0) << " ";
cout << s.Pop(0) << " ";
cout << s.Pop(0) << " ";
cout << s.Pop(1) << " ";
cout << s.Pop(1) << " ";
cout << s.Pop(1) << " ";
cout << s.Pop(1) << " ";
cout << s.Pop(1) << " ";
//cout<<s.Top(1);
}
int main()
{
test1();
test2();
system("pause");
return 0;
}一前一后向中间走：
#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
using namespace std;
template<class T>
class TwoStack
{
public:
TwoStack(int size)
:_top1(-1), _top2(size), _len(size)
{
_arr = new T[size];
}
~TwoStack()
{
if (_arr)
{
delete[] _arr;
}
}
void Push(int index, int data);
T Pop(int index);
bool IsEmpty(int index);
void Disp();
T Top(int index);
private:
int _top1;
int _top2;
int _len;
T* _arr;
};
template<class T>
void TwoStack<T>::Push(int index, int data)
{
if (_top1 >= _top2 - 1)
{
cout << "Stack is overflow" << endl;
return;
}
if (index == 0)
{
_top1++;
_arr[_top1] = data;
}
else
{
_top2--;
_arr[_top2] = data;
}
}
template<class T>
T TwoStack<T>::Pop(int index)
{
int ret;
if (index == 0)
{
if (_top1 < 0)
{
cout<<"Stack1 is null"<<endl;
return -1;
}
else
{
ret = _arr[_top1];
_top1--;
}
}
else
{
if (_top2 > _len)
{
cout << "Stack2 is null" << endl;
return -1;
}
else
{
ret = _arr[_top2];
_top2++;
}
}
return ret;
}
template<class T>
bool TwoStack<T>::IsEmpty(int index)
{
if (index == 0 && _top1 < 0)
return true;
if (index == 1 && _top2 >= _len)
return true;
return false;
}
template<class T>
void TwoStack<T>::Disp()
{
{
for (int i = 0; i < _len; i++)
{
cout << _arr[i] << " ";
}
}
}
template<class T>
T TwoStack<T>::Top(int index)
{
if (0 == index && _top1>=0)
{
return _arr[_top1];
}
if (1 == index && _top2 < _len)
{
return _arr[_top2];
}
cout << "NO TOP" << endl;
exit(0);
}
void test1()
{
TwoStack<int>s(10);
s.Push(0, 1);
s.Push(0, 2);
s.Push(0, 3);
s.Push(0, 4);
s.Push(0, 5);
//s.Push(0, 5);
s.Push(1, 6);
s.Push(1, 7);
s.Push(1, 8);
s.Push(1, 9);
s.Push(1, 10);
//s.Push(1, 10);
s.Disp();
//cout << s.IsEmpty(1);
}
void test2()
{
TwoStack<int>s(10);
s.Push(0, 1);
s.Push(0, 2);
s.Push(0, 3);
s.Push(0, 4);
s.Push(0, 5);
s.Push(1, 6);
s.Push(1, 7);
s.Push(1, 8);
s.Push(1, 9);
s.Push(1, 10);
//cout<<s.Top(1);
cout << s.Pop(0) << " ";
cout << s.Pop(0) << " ";
cout << s.Pop(0) << " ";
cout << s.Pop(0) << " ";
cout << s.Pop(0) << " ";
cout << s.Pop(1) << " ";
cout << s.Pop(1) << " ";
cout << s.Pop(1) << " ";
cout << s.Pop(1) << " ";
cout << s.Pop(1) << " ";
//cout<<s.IsEmpty(0);
}
int main()
{
test1();
//test2();
system("pause");
return 0;
}
动态实现增长：
#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
using namespace std;
template<class T>
class TwoStack
{
public:
TwoStack()
:_top1(-1), _top2(-1), _len(0), _arr(NULL), _capacity(0)
{
}
~TwoStack()
{
if (_arr)
{
delete[] _arr;
}
}
void Push(int index, int data);
T Pop(int index);
bool IsEmpty(int index);
void Disp();
T Top(int index);
void IncreaseCapcity();
private:
int _top1;
int _top2;
int _len;
T* _arr;
int _capacity;
};
template<class T>
void TwoStack<T>::IncreaseCapcity()
{
int top1 = _top1;
int top2 = _top2;
int size = _capacity;
_capacity = _len * 2 + 3;
int capacity = _len * 2 + 3;
int newlen = capacity;
T* tmp = new T[_capacity];
if (_arr != NULL)
{
for (int i = 0; i <= top1; i++)
{
tmp[i] = _arr[i];
}
for (int j = top1 + 1; j < size; j++)
{
tmp[--capacity] = _arr[--_len];
--newlen;
}
}
if (_arr != NULL)
{
delete[] _arr;
}
_arr = tmp;
_len = newlen;
_top2 = _len;
}
template<class T>
void TwoStack<T>::Push(int index, int data)
{
if (_top1 >= _top2 - 1)
{
IncreaseCapcity();
}
if (index == 0)
{
_top1++;
_arr[_top1] = data;
}
else
{
_top2--;
_arr[_top2] = data;
}
}
template<class T>
T TwoStack<T>::Pop(int index)
{
int ret;
if (index == 0)
{
if (_top1 < 0)
{
cout<<"Stack1 is null"<<endl;
return -1;
}
else
{
ret = _arr[_top1];
_top1--;
}
}
else
{
if (_top2 > _len)
{
cout << "Stack2 is null" << endl;
return -1;
}
else
{
ret = _arr[_top2];
_top2++;
}
}
return ret;
}
template<class T>
bool TwoStack<T>::IsEmpty(int index)
{
if (index == 0 && _top1 < 0)
return true;
if (index == 1 && _top2 >= _len)
return true;
return false;
}
template<class T>
void TwoStack<T>::Disp()
{
{
for (int i = 0; i < _capacity; i++)
{
cout << _arr[i] << " ";
}
}
}
template<class T>
T TwoStack<T>::Top(int index)
{
if (0 == index && _top1>=0)
{
return _arr[_top1];
}
if (1 == index && _top2 < _len)
{
return _arr[_top2];
}
cout << "NO TOP" << endl;
exit(0);
}
void test1()
{
TwoStack<int>s;
s.Push(0, 1);
s.Push(0, 2);
s.Push(0, 3);
s.Push(0, 4);
s.Push(0, 5);
//s.Push(0, 5);
//cout << s.Pop(0) << " ";
//cout << s.Pop(0) << " ";
//cout << s.Pop(0) << " ";
//cout << s.Pop(0) << " ";
//cout << s.Pop(0) << " ";
s.Push(1, 6);
s.Push(1, 7);
s.Push(1, 8);
s.Push(1, 9);
s.Push(1, 10);
//s.Push(1, 10);
s.Disp();
//cout << s.IsEmpty(1);
}
void test2()
{
TwoStack<int>s;
s.Push(0, 1);
s.Push(0, 2);
s.Push(0, 3);
s.Push(0, 4);
s.Push(0, 5);
s.Push(1, 6);
s.Push(1, 7);
s.Push(1, 8);
s.Push(1, 9);
s.Push(1, 10);
//cout<<s.Top(1);
cout << s.Pop(0) << " ";
cout << s.Pop(0) << " ";
cout << s.Pop(0) << " ";
cout << s.Pop(0) << " ";
cout << s.Pop(0) << " ";
cout << s.Pop(1) << " ";
cout << s.Pop(1) << " ";
cout << s.Pop(1) << " ";
cout << s.Pop(1) << " ";
cout << s.Pop(1) << " ";
//cout<<s.IsEmpty(0);
}
int main()
{
test1();
//test2();
system("pause");
return 0;
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