【面试题】剑指offer14

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题目：
调整数组数据使奇数全部在偶数前面
解法一：

void oddnumberfront1(int *arr,int length){    if (arr==NULL||length==0)    {        return;    }    int* first;    int* last;    first=arr;    last=arr+length-1;    while(first<last)    {        while(first<last&&(*first& 0x1)!=0)        {            first++;        }        while (first<last&&(*last& 0x1)==0)        {            last--;        }        if(first<last)        {            int tmp=*first;            *first=*last;            *last=tmp;        }    }}

这种解法比较单一，只能解答这一种问题
解法二：将判断是否为偶数单独作为一个函数，这样要是限制条件改变后，只改变这个函数即可，下面添加了可被3整除的在后面，不被的在前面

#include<iostream>#include<cstdlib>using namespace std;bool isEven(int n)//判断是否为偶数{    return (n&1)==0;}bool is3multiplc(int n)//判断是否可以被3整除{    return (n%3)==0;}void Reorder(int *arr,int length,bool(*func)(int)){    if(arr==NULL||length==0)        return;    int * first=arr;    int * last=arr+length-1;    while(first<last)    {        while (first<last&&!isEven(*first))        {            first++;        }        while (first<last&&isEven(*last))        {            last--;        }        if(first<last)        {            int tmp=*first;            *first=*last;            *last=tmp;        }    }}void mulitplc(int *arr,int length,bool(*func)(int)){    if(arr==NULL||length==0)        return;    int * first=arr;    int * last=arr+length-1;    while(first<last)    {        while (first<last&&!is3multiplc(*first))        {            first++;        }        while (first<last&&is3multiplc(*last))        {            last--;        }        if(first<last)        {            int tmp=*first;            *first=*last;            *last=tmp;        }    }}void ReorderOddEven(int * arr,int length){    Reorder(arr,length,isEven);}void muliptlc3front(int * arr,int length){    mulitplc(arr,length,isEven);}void printArr(int* arr,int length){    if(arr==NULL||length==0)        return;    for (int i=0;i<length;i++)    {        cout<<arr[i]<<" ";    }    cout<<endl;}void test1(){    int arr[]={1,2,3,4,5,6,7,8,9};    ReorderOddEven(arr,9);    printArr(arr,9);                }void test2(){    int arr1[]={1};    ReorderOddEven(arr1,1);    printArr(arr1,1);}void test3(){    int* arr2=NULL;    ReorderOddEven(arr2,0);    printArr(arr2,0);}void test4(){    int arr[]={1,2,3,4,5,6,7,8,9};    muliptlc3front(arr,9);    printArr(arr,9);}int main(){    cout<<"test1:"<<endl;    test1();    cout<<"test2:"<<endl;    test2();    cout<<"test3:"<<endl;    test3();    cout<<"test4:"<<endl;    test4();    system("pause");    return 0;}

结果

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