🐣 문제

링크 : https://www.acmicpc.net/problem/2580

🐥 코드

#include <iostream>
using namespace std;

int board[9][9];

bool check(int y, int x, int n){
  for(int i = 0; i < 9; i++){
    if(board[y][i] == n) return false;
    if(board[i][x] == n) return false;
  }

  for(int i = (y / 3) * 3; i < (y / 3) * 3 + 3; i++)
    for(int j = (x / 3) * 3; j < (x / 3) * 3 + 3; j++)
      if(board[i][j] == n) return false;

  return true;
}

void dfs(int y, int x){
  if(x == 9) {
	y++; 
	x = 0;
  }

  if(y == 9){
    for(int i = 0; i < 9; i++){
      for(int j = 0; j < 9; j++)
        cout << board[i][j] << " ";
      cout << '\n';
    }
    exit(0);
  }

  if(board[y][x]!=0){
    dfs(y,x+1);
    return;
  }

  for(int i = 1; i <= 9; i++){
    if(check(y,x,i)){
      board[y][x] = i;
      dfs(y,x+1);
      board[y][x] = 0;
    }
  }
}

int main(){
  for(int i = 0; i < 9; i++)
    for(int j = 0; j < 9; j++)
      cin >> board[i][j];

  dfs(0,0);

  return 0;
}