##### Canadian Computing Competition: 2020 Stage 1, Junior #5, Senior #2

You have to determine if it is possible to escape from a room. The room is an -by- grid with each position (cell) containing a positive integer. The rows are numbered and the columns are numbered . We use to refer to the cell in row and column .

You start in the top-left corner at and exit from the bottom-right corner at . If you are in a cell containing the value , then you can jump to any cell satisfying . For example, if you are in a cell containing a , you can jump to cell .

Note that from a cell containing a , there are up to four cells you can jump to: , or . If the room is a -by- grid, there isn't a row so only the first three jumps would be possible.

#### Input Specification

The first line of the input will be an integer . The second line of the input will be an integer . The remaining input gives the positive integers in the cells of the room with rows and columns. It consists of lines where each line contains positive integers, each less than or equal to , separated by single spaces.

For of the available marks, and .

For an additional of the available marks, .

For an additional of the available marks, all of the integers in the cells will be unique.

For an additional of the available marks, and .

#### Output Specification

Output `yes`

if it is possible to escape from the room. Otherwise, output `no`

.

#### Sample Input

```
3
4
3 10 8 14
1 11 12 12
6 2 3 9
```

#### Output for Sample Input

`yes`

#### Explanation of Output for Sample Input

Starting in the cell at which contains a , one possibility is to jump to the cell at . This cell contains an so from it, you could jump to the cell at . This brings you to a cell containing from which you can jump to the exit at . Note that another way to escape is to jump from the starting cell to the cell at to the cell at to the exit.

**Notes**

The online grader begins by testing submissions using the sample input. All other tests are skipped if the sample test is not passed. If you are only attempting the first three subtasks (the first marks), then you might want to handle the specific values of the sample input as a special case.

For the final subtask (worth marks), if you are using Java, then

`Scanner`

will probably take too long to read in the large amount of data. A much faster alternative is`BufferedReader`

.

## Comments

I'm having trouble staying below the memory limit. Can someone give me a hint?

Try to use

dynamicarray or listhow to not tle on batch 7?

Your getPairs function looks through 1 to N for every space added to the queue which is too slow. Try finding a faster way to look for factors.

My code gives a NameError on the first case? It woks fine on the CCC Grader.

Please read the tips page. In particular,

Can anyone explain why I am getting TLE at the end of Batch 6 even though I am just implementing BFS on my program (c++)

It is because your BFS function contains a

`searchm`

function which runs in every iteration, probably taking up to .TFW you spent 40 whole minutes during the CCC thinking you can only jump to adjacent cells.

Disregard this comment, I'm blind.

AC in CCC and TLE on DMOJ. (finally solved it)

Any tips on how to not TLE even with C++?

Having a loop to find all the factors of the number in the current cell is too slow. Try to find an approach that avoids this.

ok thanks

You could do it relatively fast if you just precompute the factors when you're taking input