ambigous調用遞歸sudoku_backtracker函數。

Question

這是我通過使用回溯算法解決數獨謎題的程序。該程序將遞歸調用自身，直到它被解決或無法解決。問題是，當我運行它時，編譯器說sudoku_solver.cpp第19行中的sudoku_backtracker（）函數調用是不明確的。有人可以向我解釋爲什麼這麼說，我該如何解決。如果還有其他問題，我也會很感激幫助。非常感謝。

#include <iostream> 
#include <string> 
#include <sstream> 
#include <vector> 
#include "sudoku_solver.hpp" 

int main() 
{ 


    std::vector< std::vector<int> > board(9,std::vector<int>(9)); 

    int i =0,j=0; 

    for(std::string line;std::getline(std::cin,line);) 
    { 
     if(i==9) 
     { 
      i=0; 
      break; 
     } 

     std::stringstream line_stream(line); 
     for(std::string token;std::getline(line_stream,token,' ');) 
     { 
      if(j==9) 
      { 
       j=0; 
      } 
      board[i][j] = std::stoi(token); 
      j++; 
     } 
     i++; 
    } 

    if(sudoku_backtracker(board)==1) 
    { 
     for(int i = 0;i<9;i++) 
     { 
      for(int j = 0;j<9;j++) 
      { 
       std::cout<<board[i][j]; 
      } 
      std::cout<<endl; 
     } 
    } 
    return 0; 
} 

/* This is sudoku_solver.hpp placed here for better organization on stackoverflow*/ 


#ifndef __SUDOKU_SOLVER_HPP__ 
#define __SUDOKU_SOLVER_HPP__ 
#include <vector> 

int sudoku_backtracker(std::vector< std::vector<int> > board); 

std::pair<int, int> find_empty_spot(std::vector< std::vector<int> > board); 

bool checks_num_is_valid(std::vector< std::vector<int> > board,int row,int column,int number); 

#endif //__SUDOKU_SOLVER_HPP__ 

/*this is sudoku_solver.cpp but I placed it after the header file so I can put it in block on stackoverflow*/ 


#include "sudoku_solver.hpp" 
#include <iostream> 
#include <string> 

int sudoku_backtracker(std::vector< std::vector<int> > &board) 
{ 
    int test_num = 1; 
    std::pair<int,int> empty_spot = find_empty_spot(board); 
    if(empty_spot.first == -1) 
    { 
     return 1; 
    } 

    while(test_num != 10) 
    { 
     if(checks_num_is_valid(board,empty_spot.first,empty_spot.second,test_num)) 
     { 
      board[empty_spot.first][empty_spot.second] = test_num; 
      int recursive_sudoku = sudoku_backtracker(board); 
      if(recursive_sudoku==1) 
      { 
       return 1; 
      } 
      board[empty_spot.first][empty_spot.second] = 0; 
     } 

     test_num++; 
    } 
    return 0; 
} 


std::pair<int, int> find_empty_spot(std::vector< std::vector<int> > board,int row,int column) 
{ 
    for(int row=0;row<9;row++) 
    { 
     for(int column=0;column<9;column++) 
     { 
      if(board[row][column] == 0){return std::make_pair(row,column);} 
     } 
    } 
    return std::make_pair(-1,-1); 
} 

bool checks_num_is_valid(std::vector< std::vector<int> > board, int row,int column, int number) 
{ 
    bool num_not_in_column = true; 
    bool num_not_in_row = true; 
    bool num_not_in_box = true; 
    //box_start_row as bsr and box_start_column as bsc 
    //this is the starting point to check the numbers inside the box and make 
    //sure the test number is valid 
    int bsr = 0,bsc = 0; 

    //checks the numbers in the same column but different rows 
    for(int i =0;i<9;i++) 
    { 
     if(i==row){continue;} 
     if(board[i][column] == number){num_not_in_column = false;break;} 
    } 
    //checks numbers in the same row but different columns 
    for(int i = 0;i<9;i++) 
    { 
     if(i==column){continue;} 
     if(board[row][i] == number){num_not_in_row = false;break;} 
    } 

    //checks wether the numer is int the same box 
    if(row<=2){bsr =0;} 
    if(row>=3 && row<=5){bsr = 3;} 
    if(row>=6 && row<=8){bsr = 6;} 
    if(column <=2){bsc =0;} 
    if(column>=3 && column<=5){bsc=3;} 
    if(column>=6 && column<=8){bsc=6;} 
    //double for loop to check all the values inside the box 
    for(bsr;bsr<bsr+3;bsr++) 
    { 
     for(bsc;bsc<bsc+3;bsc++) 
     { 
      if(bsr==row && bsc==column) 
      {continue;} 
      else 
      { 
       if(board[bsr][bsc] == number) 
       { 
        num_not_in_box = false; 
       } 
      } 
     } 
    } 
    bool result = num_not_in_row && num_not_in_column && num_not_in_box; 
    return result; 
} 

Answer 1

聲明：

int sudoku_backtracker(std::vector< std::vector<int> > board); 

不匹配的定義：

int sudoku_backtracker(std::vector< std::vector<int> > &board) { ... } 
                 ^^^