Question

我在寻找如何将一个元素从2D数组存储到1D数组时遇到麻烦。一旦存储了这些索引，我就需要相互交换元素。另外，我完全理解使用“ using namespace std;”虽然不是最佳实践，但是这是本课程所要求的。这是我到目前为止的内容：

#include <iostream>
#include <iomanip>
using namespace std;

//function prototypes
void minVal(int array2D[4][4], int array1D[], int numElements);
void maxVal(int array2D[4][4], int array1D[], int numElements);
void swapValues(int array2D[4][4], int array1D[], int numElements);


int main() {
    //begin program
    cout << "Array Swap Program" << endl;
    cout << "---------------------------" << endl;

    //initialize 2D array
    int twoDimensionalArray[4][4] = {
            {9, 8, 16, 7},
            {11, 6, 3, 14},
            {13, 4, 5, 12},
            {15, 1, 2, 10}
    };

    //display 2D array to user
    cout << "Below is the two dimensional array: " << endl;
    int row = 4;
    int column = 4;
    for (int i = 0; i < column; i++){
        for (int j = 0; j < row; j++){
            cout << twoDimensionalArray[i][j] << ' ';
        }//end inner for loop
        cout << endl;
    }//end outer for loop

    //initialize 1D array
    int oneDimensionalArray[4] = {{}, {}, {}, {}};


    //find minimum value using minVal function prototype
    minVal(twoDimensionalArray, oneDimensionalArray, 16);

    //find maximum value using maxVal function prototype
    maxVal(twoDimensionalArray, oneDimensionalArray, 16);
    return 0;
}

//function descriptions

//Minimum Value Void Function
void minVal(int array2D[4][4], int array1D[], int numElements){
    cout << "Searching array for minimum vale." << endl;
    cout << "Please wait..." << endl;

    //assign first element to the high variable
    int min = array2D[0][0];
    int row;
    int column;

    //begin search with second element
    for (int sub = 1; sub < numElements; sub += 1){
        if (array2D[0][sub] < min){
            min = array2D[0][sub];
            array1D[0] = array2D[0][sub];
        }//end if
    }//end for
    cout << "The minimum value of the 2D array is: " << min << endl;



    //assign row index to 1D array's first element
    cout << "It's located at row: " << array1D[0] << endl;


}//end of minVal

//Maximum Value Void Function
void maxVal(int array2D[4][4], int array1D[], int numElements){
    cout << "Searching array for maximum value." << endl;
    cout << "Please wait..." << endl;

    //assign first element to the high variable
    int max = array2D[0][0];

    //begin search with second element
    for (int sub = 1; sub < numElements; sub += 1){
        if (array2D[0][sub] > max){
            max = array2D[0][sub];
        }//end if
    }//end for
    cout << "The maximum value of the 2D array is: " << max << endl;
}//end of maxVal

我希望输出是oneDimensionalArray的索引值为

{{{2D数组的minVal行索引}，{2D数组的minVal列索引}，{2D数组的maxVal行索引}，{2D数组的maxVal列索引}};

然后应该交换2D数组中列出的最小值和最大值。

我也希望能获得有关如何找到这些东西的解释，而不仅仅是解决方案。谢谢！

Answer 1

由于二维数组将其元素存储在连续的内存中，因此您可以使用std::minmax_element和std::distance来获取最小值和最大值，以及距数组开头的距离。

这是一个小例子：

#include <iostream>
#include <algorithm>

int main() 
{
    //initialize 2D array
    int twoDimensionalArray[4][4] = {
            {9, 8, 16, 7},
            {11, 6, 3, 14},
            {13, 4, 5, 12},
            {15, 1, 2, 10}
    };

    // get both the minimum and maximum element in the 2D array
    auto pr = std::minmax_element(&twoDimensionalArray[0][0], &twoDimensionalArray[3][4]);

    // get the distances 
    auto dist_min = std::distance(&twoDimensionalArray[0][0], pr.first);
    auto dist_max = std::distance(&twoDimensionalArray[0][0], pr.second);
    std::cout << "Min Value: " << *(pr.first) <<  "  Distance: " << dist_min << "\n";
    std::cout << "Max Value: " << *(pr.second) << "  Distance: " << dist_max;
}

输出：

Min Value: 1  Distance: 13
Max Value: 16  Distance: 2

Live Example

请注意std::minmax_element的用法-参数基本上是2D数组中第一个元素的地址，以及2D数组中最后一个元素之后的地址。这样就为我们提供了搜索范围，并且就用于前两个参数的迭代器而言，符合minmax_element的要求。

如果保证矩阵是正方形的，那么我们可以使用模和除法的一小部分数学运算来获得最小值和最大值的行和列：

#include <iostream>
#include <algorithm>

int main() 
{
    //initialize 2D array
    int twoDimensionalArray[4][4] = {
            {9, 8, 16, 7},
            {11, 6, 3, 14},
            {13, 4, 5, 12},
            {15, 1, 2, 10}
    };

    auto pr = std::minmax_element(&twoDimensionalArray[0][0], &twoDimensionalArray[3][4]);
    auto dist_min = std::distance(&twoDimensionalArray[0][0], pr.first);
    auto dist_max = std::distance(&twoDimensionalArray[0][0], pr.second);
    int row_min = dist_min / 4;
    int col_min = dist_min % 4;
    int row_max = dist_max / 4;
    int col_max = dist_max % 4;
    std::cout << "Min Value: " << *(pr.first) << "\n" << "Min Location: (" << row_min << "," << col_min << ")\n\n";
    std::cout << "Max Value: " << *(pr.second) << "\n" << "Max Location: (" << row_max << "," << col_max << ")\n";
}

输出：

Min Value: 1
Min Location: (3,1)

Max Value: 16
Max Location: (0,2)

因此，如果要使用此解决方案，则只需调整代码，以便将行和列索引值保存在已声明的一维数组中。

Live Example

如何将元素的索引从2D数组存储到1D数组然后交换这些值

1 个答案: