c++ - 对整数指针数组进行排序

Question

int arr1[] = { 3, 9, 6, 7 }, arr2[] = { 2, 5, 1 }, arr3[] = { 0 },
arr4[] = { 1, 6 }, arr5[] = { 4, 5, 6, 2, 1 };
int* pointersArray[5] = { &arr1, &arr2, &arr3, &arr4, &arr5 };    
for (k = 0; k< 5; k++)
{
    for (i = 0; i < **(pointersArray + k)+1; i++)
    {
        for (j = i + 1; j < **(pointersArray + k); ++j)
        {
            if ((*(*(pointersArray + k) + i)) > *(*(pointersArray + k) + j))
            {
                temp = *(*(pointersArray + k) + i);
                *(*(pointersArray + k) + i) = *(*(pointersArray + k) + j);
                *(*(pointersArray + k) + j) = temp;
            }
        }
        printf("\n");
    }
}
for (j = 0; j < 5; j++)
{
    for (i = 0; i < **(pointersArray + j) + 1; i++)
    {
        printf("%d", *(*(pointersArray + j) + i));
    }
    printf(" ");
}

我想对 pointersArray 中的每个数组进行排序(每个数组的大小是第一个单元格 + 1)而不对第一个单元格进行排序。以上是我的非工作代码，有修复它的想法吗？

输出:

3697
251
0
16
256

预期输出:

3679
215
0
16
41256

Answer 1

给你。

#include <stdio.h>

int main( void )
{
    int arr1[] = { 3, 9, 6, 7 };
    int arr2[] = { 2, 5, 1 };
    int arr3[] = { 0 };
    int arr4[] = { 1, 6 };
    int arr5[] = { 4, 5, 6, 2, 1 };

    int * pointersArray[] = { arr1, arr2, arr3, arr4, arr5 };   
    const size_t N = sizeof( pointersArray ) / sizeof( *pointersArray );

    for ( size_t k = 0; k < N; ++k )
    {
        size_t n = *pointersArray[k];

        for ( size_t i = 0; i < n; i++ )
        {
            for ( size_t j = 1; j < n - i; j++ )
            {
                if ( pointersArray[k][j+1] < pointersArray[k][j] )
                {
                    int tmp = pointersArray[k][j+1];
                    pointersArray[k][j+1]  = pointersArray[k][j];
                    pointersArray[k][j] = tmp;
                }
            }
        }
    }

    for ( size_t k = 0; k < N; ++k )
    {
        size_t n = *pointersArray[k] + 1;
        for ( size_t i = 0; i < n; i++ ) printf( "%d ", pointersArray[k][i] );
        printf( "\n" );
    }        

}

程序输出为

3 6 7 9 
2 1 5 
0 
1 6 
4 1 2 5 6 

考虑到如果使用标准 C 函数 qsort 会更简单，代码看起来更清晰而不是手动编写冒泡排序函数。

例如

#include <stdlib.h>
#include <stdio.h>

int cmp( const void *lhs, const void *rhs )
{
    int a = *( int * )lhs;
    int b = *( int * )rhs;

    return ( b < a ) - ( a < b );
}

int main( void )
{
    int arr1[] = { 3, 9, 6, 7 };
    int arr2[] = { 2, 5, 1 };
    int arr3[] = { 0 };
    int arr4[] = { 1, 6 };
    int arr5[] = { 4, 5, 6, 2, 1 };

    int * pointersArray[] = { arr1, arr2, arr3, arr4, arr5 };   
    const size_t N = sizeof( pointersArray ) / sizeof( *pointersArray );

    for ( size_t i = 0; i < N; ++i )
    {
        qsort( pointersArray[i] + 1, *pointersArray[i], sizeof( int ), cmp ); 
    }

    for ( size_t k = 0; k < N; ++k )
    {
        size_t n = *pointersArray[k] + 1;
        for ( size_t i = 0; i < n; i++ ) printf( "%d ", pointersArray[k][i] );
        printf( "\n" );
    }        

}

输出将与上面所示相同

3 6 7 9 
2 1 5 
0 
1 6 
4 1 2 5 6 

在 C++ 中，您可以使用标准算法 std::sort在 header <algorithm> 中声明。 例如

#include <iostream>
#include <algorithm>

int main()
{
    int arr1[] = { 3, 9, 6, 7 };
    int arr2[] = { 2, 5, 1 };
    int arr3[] = { 0 };
    int arr4[] = { 1, 6 };
    int arr5[] = { 4, 5, 6, 2, 1 };

    int * pointersArray[] = { arr1, arr2, arr3, arr4, arr5 };   

    for ( auto p : pointersArray )
    {
        std::sort( p + 1, p + 1 + *p ); 
    }

    for ( auto p : pointersArray )
    {
        size_t n = *p + 1;
        for ( size_t i = 0; i < n; i++ ) std::cout << p[i] << ' ';
        std::cout << std::endl;
    }        

}

输出为

3 6 7 9 
2 1 5 
0 
1 6 
4 1 2 5 6