JZ-C-14

剑指offer第十四题：调整数组顺序使得奇数在偶数之前

//============================================================================
// Name        : JZ-C-14.cpp
// Author      : Laughing_Lz
// Version     :
// Copyright   : All Right Reserved
// Description :调整数组顺序使得奇数在偶数之前
//============================================================================

#include <iostream>
#include <stdio.h>
using namespace std;

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); //将判断标准函数指针作参数传入，修改判断标准函数即可实现模式应用
}

void Reorder(int *pData, unsigned int length, bool (*func)(int)) { //函数指针：同：typedef bool (*FuncPointer)(int); FunPointer func = isEven;
    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	", numbers[i]);

    printf("
");
}

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

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

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

    printf("Test for solution 2:
");
    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 main(int argc, char** argv) {
    Test1();
    Test2();
    Test3();
    Test4();
    Test5();
    Test6();

    return 0;
}