一个数组模拟两个栈

#include <cstdlib> #include <iostream> #include <assert.h> using namespace std; class mystack { public: mystack(int _n) { n = _n; arr = new int[_n]; memset(arr, 0, n); size1 = -1; size2 = _n; } void push1(int element) { if(size2 - size1 > 1) { size1++; arr[size1] = element; } } void pop1() { if(size1 >= 0) { arr[size1] = 0; size1--; } } int top1() { assert(size1 >= 0); return arr[size1]; } bool empty1() { return !(size1 >= 0); } /*第二个栈*/ void push2(int element) { if(size2 - size1 > 1) { size2--; arr[size2] = element; } } void pop2() { if(size2 <= n-1) { arr[size2] = 0; size2++; } } int top2() { assert(size2 <= n-1); return (arr[size2]); } bool empty2() { return !(size2 < n); } ~mystack() { delete []arr; } private: int *arr; int size1; int size2; int n; }; int main(int argc, char *argv[]) { mystack my(20); for(int i=0; i<6; i++) { my.push1(i); my.push2(20 - i); } while (!my.empty1()) { cout<<my.top1()<<" "; my.pop1(); } cout<<endl; while (!my.empty2()) { cout<<my.top2()<<" "; my.pop2(); } cout<<endl; system("PAUSE"); return EXIT_SUCCESS; }  

算法思想：为了节省空间，叫两个栈共享一个数组，一个是从底部向上增长，一个是从上向下递减，当两个栈的栈顶相遇时，说明这个栈满了