面试题22之栈的压入弹出序列_StackPushPopOrder.cpp

// StackPushPopOrder.cpp : Defines the entry point for the console application.
//

// 《剑指Offer——名企面试官精讲典型编程题》代码
// 著作权所有者：何海涛

#include "stdafx.h"
#include <stack>

bool IsPopOrder(const int* pPush, const int* pPop, int nLength)
{
    bool bPossible = false;

    if(pPush != NULL && pPop != NULL && nLength > 0)
    {
        const int* pNextPush = pPush;
        const int* pNextPop = pPop;

        std::stack<int> stackData;

        while(pNextPop - pPop < nLength)
        {
            // 当辅助栈的栈顶元素不是要弹出的元素
            // 先压入一些数字入栈
            while(stackData.empty() || stackData.top() != *pNextPop)
            {
                // 如果所有数字都压入辅助栈了，退出循环
                if(pNextPush - pPush == nLength)
                    break;

                stackData.push(*pNextPush);

                pNextPush ++;
            }

            if(stackData.top() != *pNextPop)
                break;

            stackData.pop();
            pNextPop ++;
        }

        if(stackData.empty() && pNextPop - pPop == nLength)
            bPossible = true;
    }

    return bPossible;
}

// ====================测试代码====================
void Test(char* testName, const int* pPush, const int* pPop, int nLength, bool expected)
{
    if(testName != NULL)
        printf("%s begins: ", testName);

    if(IsPopOrder(pPush, pPop, nLength) == expected)
        printf("Passed.\n");
    else
        printf("failed.\n");
}

void Test1()
{
    const int nLength = 5;
    int push[nLength] = {1, 2, 3, 4, 5};
    int pop[nLength] = {4, 5, 3, 2, 1};
    
    Test("Test1", push, pop, nLength, true);
}

void Test2()
{
    const int nLength = 5;
    int push[nLength] = {1, 2, 3, 4, 5};
    int pop[nLength] = {3, 5, 4, 2, 1};
    
    Test("Test2", push, pop, nLength, true);
}

void Test3()
{
    const int nLength = 5;
    int push[nLength] = {1, 2, 3, 4, 5};
    int pop[nLength] = {4, 3, 5, 1, 2};
    
    Test("Test3", push, pop, nLength, false);
}

void Test4()
{
    const int nLength = 5;
    int push[nLength] = {1, 2, 3, 4, 5};
    int pop[nLength] = {3, 5, 4, 1, 2};
    
    Test("Test4", push, pop, nLength, false);
}

// push和pop序列只有一个数字
void Test5()
{
    const int nLength = 1;
    int push[nLength] = {1};
    int pop[nLength] = {2};

    Test("Test5", push, pop, nLength, false);
}

void Test6()
{
    const int nLength = 1;
    int push[nLength] = {1};
    int pop[nLength] = {1};

    Test("Test6", push, pop, nLength, true);
}

void Test7()
{
    Test("Test7", NULL, NULL, 0, false);
}
 
int _tmain(int argc, _TCHAR* argv[])
{
    Test1();
    Test2();
    Test3();
    Test4();
    Test5();
    Test6();
    Test7();

    return 0;
}