From 0830231f753423a128706b7bd97c07dd45334141 Mon Sep 17 00:00:00 2001
From: SirajDarbi <sirajdarbi@hotmail.com>
Date: Tue, 30 Jan 2024 03:56:52 +0000
Subject: [PATCH] solution to task

---
 sudoku.go | 80 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 80 insertions(+)

diff --git a/sudoku.go b/sudoku.go
index 06ab7d0..0500e1e 100644
--- a/sudoku.go
+++ b/sudoku.go
@@ -1 +1,81 @@
 package main
+
+import "fmt"
+
+// SolveSudoku takes a 9x9 Sudoku grid with zeros representing empty cells and solves the puzzle.
+func SolveSudoku(grid [][]int) bool {
+    if isSolved(grid) {
+        return true
+    }
+
+    for row := 0; row < 9; row++ {
+        for col := 0; col < 9; col++ {
+            if grid[row][col] == 0 {
+                for num := 1; num <= 9; num++ {
+                    if isValid(grid, row, col, num) {
+                        grid[row][col] = num
+                        if SolveSudoku(grid) {
+                            return true
+                        }
+                        grid[row][col] = 0 // backtrack
+                    }
+                }
+                return false // trigger backtracking
+            }
+        }
+    }
+    return true // puzzle is solved
+}
+
+// isSolved checks if the Sudoku puzzle is already solved.
+func isSolved(grid [][]int) bool {
+    for row := range grid {
+        for col := range grid[row] {
+            if grid[row][col] == 0 {
+                return false
+            }
+        }
+    }
+    return true
+}
+
+// isValid checks if placing num in grid[row][col] is valid per Sudoku rules.
+func isValid(grid [][]int, row, col, num int) bool {
+    for i := 0; i < 9; i++ {
+        // Check row and column
+        if grid[row][i] == num || grid[i][col] == num {
+            return false
+        }
+
+        // Check 3x3 subgrid
+        subRow := 3 * (row / 3)
+        subCol := 3 * (col / 3)
+        if grid[subRow+i/3][subCol+i%3] == num {
+            return false
+        }
+    }
+    return true
+}
+
+func main() {
+    grid := [][]int{
+        {5, 3, 0, 0, 7, 0, 0, 0, 0},
+        {6, 0, 0, 1, 9, 5, 0, 0, 0},
+        {0, 9, 8, 0, 0, 0, 0, 6, 0},
+        {8, 0, 0, 0, 6, 0, 0, 0, 3},
+        {4, 0, 0, 8, 0, 3, 0, 0, 1},
+        {7, 0, 0, 0, 2, 0, 0, 0, 6},
+        {0, 6, 0, 0, 0, 0, 2, 8, 0},
+        {0, 0, 0, 4, 1, 9, 0, 0, 5},
+        {0, 0, 0, 0, 8, 0, 0, 7, 9},
+    }
+
+    if SolveSudoku(grid) {
+        fmt.Println("Sudoku Solved:")
+        for _, row := range grid {
+            fmt.Println(row)
+        }
+    } else {
+        fmt.Println("No solution exists")
+    }
+}