数独检测器：帝国理工C++作业

#include <fstream>
#include <vector>
#include <iostream>
#include <string>
using namespace std;

bool check_sudoku(const vector<int>& input);
int coordtoidx(int row, int col);
void extract_row(const vector<int>& input, int row, vector<int>& output);
void extract_col(const vector<int>& input, int col, vector<int>& output);
void extract_subsquare(const vector<int>& input, int row, int col, vector<int>& output);
bool once(int num,const vector<int>& input);

int main()
{
ifstream infile;
cout<<"Please input a input file name"<<endl;
string infilename;
cin>>infilename;
infile.open(infilename);
if (!infile.is_open())
{
cout<<"could not open input file"<<endl;
system("pause");
exit(EXIT_FAILURE);
}

vector<int> input;
int number;
while (infile>>number)
{
input.push_back(number);
}
infile.close();

bool isOK=check_sudoku(input);
if (isOK)
{
cout<<"valid"<<endl;
}
else
{
cout<<"invalid"<<endl;
}

system("pause");
return 0;
}

bool check_sudoku(const vector<int>& input)
{
for (int i=0; i<9; i++)
{
vector<int> rowNumbers;
extract_row(input,i,rowNumbers);
for (int m=1;m<10;m++)
{
bool onceFlag=once(m,rowNumbers);
if(!onceFlag)
{
return false;
}
}
}
for (int j=0; j<9; j++)
{
vector<int> colNumbers;
extract_col(input,j,colNumbers);
for (int m=1;m<10;m++)
{
bool onceFlag=once(m,colNumbers);
if(!onceFlag)
{
return false;
}
}
}
for (int p=0; p<9; p=p+3)
for (int q=0; q<9; q=q+3)
{
vector<int> subsquareNumbers;
extract_subsquare(input,p,q,subsquareNumbers);
for (int m=1;m<10;m++)
{
bool onceFlag=once(m,subsquareNumbers);
if(!onceFlag)
{
return false;
}
}
}
return true;
}

int coordtoidx(int row, int col)
{
return row*9+col;
}

void extract_row(const vector<int>& input, int row, vector<int>& output)
{
for (int c=0; c<9;c++)
{
int idx=coordtoidx(row,c);
output.push_back(input.at(idx));
}
}

void extract_col(const vector<int>& input, int col, vector<int>& output)
{
for (int r=0; r<9;r++)
{
int idx=coordtoidx(r,col);
output.push_back(input.at(idx));
}
}

void extract_subsquare(const vector<int>& input, int row, int col, vector<int>& output)
{
for (int r=row; r<row+3;r++)
for (int c=col; c<col+3;c++)
{
int idx=coordtoidx(r,c);
output.push_back(input.at(idx));
}
}

bool once(int num, const vector<int>& input)
{
int count=0;
for (unsigned int i=0; i<input.size(); i++)
{
if (input.at(i)==num)
{
count++;
}
}
return count==1?true:false;
}