## Let's play the seventh Sudoku game at second level hardness

This is the seventh game play at second level Sudoku. In this game we will find a valid cell as it catches our eyes. What we mean, we won't play the game by the book, we will play as naturally and randomly as our fancy takes us. We can afford to play this way as our comfort level has increased by playing a number of earlier games and building our set of useful patterns for finding a valid cell. Generally we will use DSA technique and Cycle concept more frequently. Nevertheless quick scan of row and column will always be a staple technique.

Usually we will form the DSAs in mind and will use it when required. When we don't get any easy breakthrough, then only we start writing especially the two digit cell DSAs. More often than not, proceeding this way a little ahead, the DSAs enumerated produce a breakthrough.

To know what a **cycle** or **DSA** is, you may refer to our * first* and

*. We will straightway go for game play without any explanation.*

**second game play sessions at level 2**### The Sudoku second level game 7

**R1C3 1**, scan C1, C2 -- **R8C9 1**, scan R7, R9 -- **R9C2 4**, scan R8, C3 -- **R9C8 7**, scan R7, C7 -- **R4C3 7**, scan R5, R6 -- **R1C8 8**, scan R2, C7 -- **R7C9 5**, DSA [4,5,9] in C9 -- **R4C8 2**, long DSA [2,4,5,6] in C8 -- **R7C8 6**, DSA [4,5,6] in C8 -- **R9C7 2** -- **R7C3 3**, DSA [2,3] in R7 -- **R7C6 2** -- **R6C3 9**, DSA [5,6,9] in C3.

We will now form two digit DSAs in a few cells before we go over to the next stage.

**DSA [6,7]** in R3C1 in R3 of [1,6,7,9] -- DSA [6,9] in R3C2 in R3 of [1,6,7,9] -- DSA [6,7] in R2C1 in top left 9-square large cell of DSA [5,6,7,9]. This created a **useful cycle [6,7] in R2C1** and **R3C1**.

The following figure shows the results of our efforts till now.

Then further on **R3C2 9**, DSA cancel because of cycle -- **R1C2 5** for cycle (6,7) -- **R8C1 8**, DSA [3,8] in C1 because of cycle (6,7) -- **R5C1 3**, because of cycle (6,7) -- **R3C4 6**, DSA [1,6,7] in R3 -- **R3C1 7**, DSA cancel -- **R2C1 6** -- **R3C7 1** -- **R1C7 6**, scan R2.

Next 18 cells, **R1C4 4**, DSA [4,9] in R1 -- **R1C5 9** -- **R6C5 2**, scan R4, R5, C6 -- **R2C4 2**, scan C5, C6 -- **R5C2 6**, scan R6 -- **R6C2 8** -- **R8C2 2** -- **R4C5 6**, scan R5, R6, C4 --** R4C4 3**, DSA [3,9] in R4 -- **R4C7 9** -- **R2C9 9**, scan C7, C8 -- **R2C7 5**, DSA [4,5] in 9-cell square top right -- **R2C8 4** -- **R5C8 5** -- **R5C9 4** -- **R6C7 3** -- **R6C6 5** -- **R5C4** 8, DSA [1,8,9] in R5.

The last steps, **R8C4 5** -- **R9C3 5**, scan R8 -- **R8C3 6** -- **R8C6 7**, DSA [3,7] in R8 -- **R8C5 3** -- **R2C5 7**, scan C6 -- **R2C6 1** -- **R5C5 1**, scan C6 -- **R5C6 9** -- **R9C5 8** -- **R9C6 6. **End. Game solved.

#### A special note for you

*We haven't tried to optimize. So we feel that this more complex game is solvable by following an easier path.*

**You should try to reach one of the simpler solutions. **

Lastly, we leave a game for you to solve.

### A game for you to solve

We leave you here with a new game for you to solve. In our next session we will present its solution and another new game.

Enjoy.