void graph :: makegraph(int& n) {
int i,j;
for (i=0;i<n;i++) {
vector<int> row; // Create an empty row
for (j=0;j<n;j++) {
row.push_back(0); // Add an element (column) to the row
}
matrix.push_back(row); // Add the row to the main vector
}
}
