Question

我想从文件中读取Graph并启动函数以获得最大流量，但是当我将此图作为函数参数传递时，我得到一些错误。我做错了什么？

int main() {
fstream file;
file.open( "macierz.txt", ios::in );

int n = 7;
int graph[n][n];

int v;
for(int i = 0; i < n; i++){
    for(int j = 0 ; j < n; j++){
        file >> v;
        graph[i][j] = v;
    }
}

cout << "Ford-Fulkerson -MATRIX- The maximum possible flow: " << fordFulkersonMatrix(graph, 0, 6) << endl;

功能：

int fordFulkersonMatrix(int graph[7][7], int start, int target) {
int u, v;
int rGraph[7][7];
int parent[7];
int max_flow = 0;

for (u = 0; u < 7; u++) {
    for (v = 0; v < 7; v++)
    {
        rGraph[u][v] = graph[u][v];
    }
}

错误：

main.cpp|200|error: cannot convert 'int (*)[(((unsigned int)(((int)n) + -0x000000001)) + 1)]' to 'const int (*)[7]' for argument '1' to 'int fordFulkersonMatrix(const int (*)[7], int, int)'|

Answer 1

如果你用Java编程，肯定你会喜欢C ++ STL接口：

// or even better - use Eigen as Peter K mentioned
using MyCustomMatrix = std::vector<std::vector<int> >;

// input by const ref to prevent std::vector copy
int fordFulkersonMatrix(const MyCustomMatrix& input, int start, int target) {
    // do whatever you need to do
    // you can access your matrix elements like this:
    int elem34 = input[3][4];  // only if your matrix if big enough, of course
    // you can iterare using C++11 range loops
    for (const auto& row : input) {
        for(auto elem : row) {
            std::cout << "My elem: " << elem << std::endl;
        }
    }
    // and you can access your matrix dim information like this:
    int numRows = input.size();
    if (numRows > 0) {
        int numCols = input[0].size();
    }
    return 0;
}

稍后在代码中，您可以像这样构建矩阵：

MyCustomMatrix mat;
mat.push_back(MyCustomMatrix::value_type());  // add one row
mat[0].push_back(69);  // add one elem to the first row
fordFulkersonMatrix(mat, 0, 6);

预期产出：

My elem: 69

这当然是非常懒惰的解决方案，但也许你不需要更多。对于一些严肃的线性代数运算，考虑使用专门的库（如已经提到的Eigen，或者提升uBLAS）。

二维数组从文件中读取为参数

1 个答案: