LeetCode题解——Sudoku Solver

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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...

class Solution {public:    bool col[10][10],row[10][10],f[10][10];    bool flage=false;    void solveSudoku(vector<vector<char>>& board) {        memset(col,false,sizeof(col));        memset(row,false,sizeof(row));        memset(f,false,sizeof(f));        for(int i=0; i<9; i++){            for(int j=0; j<9; j++){                if(board[i][j]!='.'){                    int num=board[i][j]-'0';                    int k = (i/3)*3+j/3;                    row[i][num]=col[j][num]=f[k][num]=true;                }            }        }        dfs(board,0,0);    }    void dfs(vector<vector<char>>& board,int i,int j){        if(flage) return;        if(i>=9){ flage=true; return;}        if(board[i][j]!='.'){            if(j<8) dfs(board,i,j+1);            else dfs(board,i+1,0);            if(flage) return;        }        else{            int k = (i/3)*3+j/3;            for(int n=1;n<=9;n++){                if(!row[i][n] && !col[j][n] && !f[k][n]){                    board[i][j]='0'+n;                    row[i][n]=col[j][n]=f[k][n]=true;                    if(j<8) dfs(board,i,j+1);                    else dfs(board,i+1,0);                    if(flage) return;                    row[i][n]=col[j][n]=f[k][n]=false;//一次尝试失败，重置，回溯                }             }            board[i][j]='.';//当所有尝试都失败时，重置，回溯        }    }};

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