面试题14之调整数组顺序使奇数位于偶数之前_ReorderArray.cpp

// ReorderArray.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"

void Reorder(int *pData, unsigned int length, bool (*func)(int));
bool isEven(int n);

// ====================方法一====================
void ReorderOddEven_1(int *pData, unsigned int length)
{
    if(pData == NULL || length == 0)
        return;

    int *pBegin = pData;
    int *pEnd = pData + length - 1;

    while(pBegin < pEnd)
    {
        // 向后移动pBegin，直到它指向偶数
        while(pBegin < pEnd && (*pBegin & 0x1) != 0)
            pBegin ++;

        // 向前移动pEnd，直到它指向奇数
        while(pBegin < pEnd && (*pEnd & 0x1) == 0)
            pEnd --;

        if(pBegin < pEnd)
        {
            int temp = *pBegin;
            *pBegin = *pEnd;
            *pEnd = temp;
        }
    }
}

// ====================方法二====================
void ReorderOddEven_2(int *pData, unsigned int length)
{
    Reorder(pData, length, isEven);
}

void Reorder(int *pData, unsigned int length, bool (*func)(int))
{
    if(pData == NULL || length == 0)
        return;

    int *pBegin = pData;
    int *pEnd = pData + length - 1;

    while(pBegin < pEnd) 
    {
        // 向后移动pBegin
        while(pBegin < pEnd && !func(*pBegin))
            pBegin ++;

        // 向前移动pEnd
        while(pBegin < pEnd && func(*pEnd))
            pEnd --;

        if(pBegin < pEnd)
        {
            int temp = *pBegin;
            *pBegin = *pEnd;
            *pEnd = temp;
        }
    }
}

bool isEven(int n)
{
    return (n & 1) == 0;
}

// ====================测试代码====================
void PrintArray(int numbers[], int length)
{
    if(length < 0)
        return;

    for(int i = 0; i < length; ++i)
        printf("%d\t", numbers[i]);

    printf("\n");
}

void Test(char* testName, int numbers[], int length)
{
    if(testName != NULL)
        printf("%s begins:\n", testName);

    int* copy = new int[length];
    for(int i = 0; i < length; ++i)
    {
        copy[i] = numbers[i];
    }

    printf("Test for solution 1:\n");
    PrintArray(numbers, length);
    ReorderOddEven_1(numbers, length);
    PrintArray(numbers, length);

    printf("Test for solution 2:\n");
    PrintArray(copy, length);
    ReorderOddEven_2(copy, length);
    PrintArray(copy, length);

    delete[] copy;
}

void Test1()
{
    int numbers[] = {1, 2, 3, 4, 5, 6, 7};
    Test("Test1", numbers, sizeof(numbers)/sizeof(int));
}

void Test2()
{
    int numbers[] = {2, 4, 6, 1, 3, 5, 7};
    Test("Test2", numbers, sizeof(numbers)/sizeof(int));
}

void Test3()
{
    int numbers[] = {1, 3, 5, 7, 2, 4, 6};
    Test("Test3", numbers, sizeof(numbers)/sizeof(int));
}

void Test4()
{
    int numbers[] = {1};
    Test("Test4", numbers, sizeof(numbers)/sizeof(int));
}

void Test5()
{
    int numbers[] = {2};
    Test("Test5", numbers, sizeof(numbers)/sizeof(int));
}

void Test6()
{
    Test("Test6", NULL, 0);
}

int _tmain(int argc, _TCHAR* argv[])
{
    Test1();
    Test2();
    Test3();
    Test4();
    Test5();
    Test6();

    return 0;
}