updated sudoko.go with the solution code (by Dev Narula)

sudoku.go

@@ -1 +1,63 @@
 package main
+
+func SolveSudoku(board [][]int) [][]int {
+	out := make([][]int, len(board))
+	for i := range board {
+		out[i] = make([]int, len(board[i]))
+		copy(out[i], board[i])
+	}
+	solve(&out)
+	return out
+}
+
+func solve(board *[][]int) bool {
+	empty := []int{}
+	for i := 0; i < 9; i++ {
+		for j := 0; j < 9; j++ {
+			if (*board)[i][j] == 0 {
+				empty = append(empty, i, j)
+			}
+		}
+	}
+	if len(empty) == 0 {
+		//finished solving sudoku, no empty cells
+		return true
+	}
+
+	r, c := empty[0], empty[1]
+
+	for num := 1; num <= 9; num++ {
+		if isValid(*board, r, c, num) {
+			(*board)[r][c] = num
+			//recursively determine if num is valid for board[r][c]
+			if solve(board) {
+				return true
+			}
+			//if board[r][c] = num is invalid, then reset the cell
+			(*board)[r][c] = 0
+		}
+	}
+
+	return false // No valid number found for the current cell
+}
+
+func isValid(board [][]int, row, col, num int) bool {
+	// validate row and col
+	for i := 0; i < 9; i++ {
+		if board[row][i] == num || board[i][col] == num {
+			return false
+		}
+	}
+
+	// valid 3x3 subgrid for duplicates
+	x, y := 3*(row/3), 3*(col/3)
+	for i := 0; i < 3; i++ {
+		for j := 0; j < 3; j++ {
+			if board[x+i][y+j] == num {
+				return false
+			}
+		}
+	}
+	//return true if grid is valid
+	return true
+}