Sudoku Problem

Sumit Rawal answered on October 19, 2022 Popularity 6/10 Helpfulness 1/10

answer Sudoku Problem

Sudoku Problem

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import java.util.*;
import java.io.*;
import java.lang.*;

class GFG  
{ 
    public static boolean isSafe(int[][] board,int row, int col, int num) 
    { 
     
        for (int d = 0; d < board.length; d++)  
        { 
            
            if (board[row][d] == num) { 
                return false; 
            } 
        } 
  
        for (int r = 0; r < board.length; r++)  
        { 
               
            if (board[r][col] == num)  
            { 
                return false; 
            } 
        }  
        int sqrt = (int)Math.sqrt(board.length); 
        int boxRowStart = row - row % sqrt; 
        int boxColStart = col - col % sqrt; 
  
        for (int r = boxRowStart; 
             r < boxRowStart + sqrt; r++)  
        { 
            for (int d = boxColStart; 
                 d < boxColStart + sqrt; d++)  
            { 
                if (board[r][d] == num)  
                { 
                    return false; 
                } 
            } 
        } 
  
        return true; 
    } 
  
    public static boolean solveSudoku( 
        int[][] board, int n) 
    { 
        int row = -1; 
        int col = -1; 
        boolean isEmpty = true; 
        for (int i = 0; i < n; i++)  
        { 
            for (int j = 0; j < n; j++)  
            { 
                if (board[i][j] == 0)  
                { 
                    row = i; 
                    col = j; 
                    isEmpty = false; 
                    break; 
                } 
            } 
            if (!isEmpty) { 
                break; 
            } 
        } 
  
        if (isEmpty)  
        { 
            return true; 
        } 
        
        for (int num = 1; num <= n; num++)  
        { 
            if (isSafe(board, row, col, num))  
            { 
                board[row][col] = num; 
                if (solveSudoku(board, n))  
                { 
                    // print(board, n); 
                    return true; 
                } 
                else 
                { 
                    // replace it 
                    board[row][col] = 0; 
                } 
            } 
        } 
        return false; 
    } 
  
    public static void print(int[][] board, int N) 
    { 
        for (int r = 0; r < N; r++)  
        { 
            for (int d = 0; d < N; d++) 
            { 
                System.out.print(board[r][d]); 
                System.out.print(" "); 
            } 
            System.out.print("\n"); 
  
            if ((r + 1) % (int)Math.sqrt(N) == 0) 
            { 
                System.out.print(""); 
            } 
        } 
    } 
  
    public static void main(String args[]) 
    { 
  
        int[][] board = new int[][] { 
            { 3, 0, 6, 5, 0, 8, 4, 0, 0 }, 
            { 5, 2, 0, 0, 0, 0, 0, 0, 0 }, 
            { 0, 8, 7, 0, 0, 0, 0, 3, 1 }, 
            { 0, 0, 3, 0, 1, 0, 0, 8, 0 }, 
            { 9, 0, 0, 8, 6, 3, 0, 0, 5 }, 
            { 0, 5, 0, 0, 9, 0, 6, 0, 0 }, 
            { 1, 3, 0, 0, 0, 0, 2, 5, 0 }, 
            { 0, 0, 0, 0, 0, 0, 0, 7, 4 }, 
            { 0, 0, 5, 2, 0, 6, 3, 0, 0 } 
        }; 
        int N = board.length; 
  
        if (solveSudoku(board, N))  
        {  
            print(board, N); 
        } 
        else { 
            System.out.println("No solution"); 
        } 
    } 
}

Popularity 6/10 Helpfulness 1/10 Language whatever

Source: Grepper

Tags: sudoku whatever

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Contributed on Oct 19 2022

Sumit Rawal

0 Answers Avg Quality 2/10

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