标签：style blog http io ar color os 使用 sp
Write a program to solve a Sudoku puzzle by filling the empty cells.
Empty cells are indicated by the character ‘.‘.
You may assume that there will be only one unique solution.
A sudoku puzzle...
...and its solution numbers marked in red.
Backtracking Hash Table
所以在外层循环后返回true，是假如例子上的情况，最后一个格不为空，那么按上面逻辑是不会进入内部的，而如果能够全部遍历完整个矩阵，那么表示没有在内部返回，等价于成功填写了。
之所以使用 ii jj，是为了可以方便处理3*3框，在能否填写的时候，需要注意跳过自身与自身判断，先判断行列，然后框的时候变可以跳过当前框所在的行列了。
1 #include <vector> 2 #include <iostream> 3 #include <iterator> 4 using namespace std; 5 6 class Solution { 7 public: 8 void solveSudoku(vector<vector<char> > &board) { 9 help(board,0,0,0,0); 10 } 11 bool help(vector<vector<char> > & board,int i,int ii,int j,int jj){ 12 for(;i<9;i+=3){ 13 for(;ii<3;ii++){ 14 for(;j<9;j+=3){ 15 for(;jj<3;jj++){ 16 if(board[i+ii][j+jj]!=‘.‘) continue; 17 bool finish = false; 18 for(char c=‘1‘;c<=‘9‘&&!finish;c++){ 19 bool canIn= true; 20 for(int k=0;k<9&&canIn;k++){ 21 if(k!=i+ii&&board[k][j+jj]==c) canIn = false; 22 if(k!=j+jj&&board[i+ii][k]==c) canIn = false; 23 } 24 for(int ti=0;ti<3&&canIn;ti++){ 25 if(ti == ii) continue; 26 for(int tj=0;tj<3&&canIn;tj++){ 27 if(tj==jj) continue; 28 if(board[ti+i][tj+j]==c) canIn = false; 29 } 30 } 31 if(canIn==false) continue; 32 board[i+ii][j+jj] = c; 33 finish = help(board,i,ii,j,jj); 34 } 35 if(!finish){ board[i+ii][j+jj] = ‘.‘; return false; } 36 } 37 jj = 0; 38 } 39 j=0; 40 } 41 ii=0; 42 } 43 return true; 44 } 45 }; 46 47 int main() 48 { 49 vector<char> line; 50 vector<vector<char> > board; 51 line = {‘5‘,‘3‘,‘.‘,‘.‘,‘7‘,‘.‘,‘.‘,‘.‘,‘.‘}; 52 board.push_back(line); 53 line.clear(); 54 line = {‘6‘,‘.‘,‘.‘,‘1‘,‘9‘,‘5‘,‘.‘,‘.‘,‘.‘}; 55 board.push_back(line); 56 line.clear(); 57 line = {‘.‘,‘9‘,‘8‘,‘.‘,‘.‘,‘.‘,‘.‘,‘6‘,‘.‘}; 58 board.push_back(line); 59 line.clear(); 60 line = {‘8‘,‘.‘,‘.‘,‘.‘,‘6‘,‘.‘,‘.‘,‘.‘,‘3‘}; 61 board.push_back(line); 62 line.clear(); 63 line = {‘4‘,‘.‘,‘.‘,‘8‘,‘.‘,‘3‘,‘.‘,‘.‘,‘1‘}; 64 board.push_back(line); 65 line.clear(); 66 line = {‘7‘,‘.‘,‘.‘,‘.‘,‘2‘,‘.‘,‘.‘,‘.‘,‘6‘}; 67 board.push_back(line); 68 line.clear(); 69 line = {‘.‘,‘6‘,‘.‘,‘.‘,‘.‘,‘.‘,‘2‘,‘8‘,‘.‘}; 70 board.push_back(line); 71 line.clear(); 72 line = {‘.‘,‘.‘,‘.‘,‘4‘,‘1‘,‘9‘,‘.‘,‘.‘,‘5‘}; 73 board.push_back(line); 74 line.clear(); 75 line = {‘.‘,‘.‘,‘.‘,‘.‘,‘8‘,‘.‘,‘.‘,‘7‘,‘9‘}; 76 board.push_back(line); 77 Solution sol; 78 sol.solveSudoku(board); 79 for(int i=0;i<board.size();i++){ 80 copy(board[i].begin(),board[i].end(),ostream_iterator<char>(cout," ")); 81 cout<<endl; 82 } 83 return 0; 84 }
[LeetCode] Sudoku Solver 解数独,递归,回溯
标签：style blog http io ar color os 使用 sp
原文地址：http://www.cnblogs.com/Azhu/p/4141820.html
