SUDOKU

朋友send了个sudoku给我

觉得挺难的

试了两次fail, 睡了再试，就成功了

[1]这格只剩3可以填
有2，6，1 在小格
直行有456
横行有1789
Thus,only remain 3 to fill in

[2] We can get second 3 after step above
[3] 8 can be inR7C7,R7C9 orR9C7
If we put in R7, then 8 cannot fill in FOR CELL8
THUS, it only can be in R9C7

[4] column 7,{1,2}only can be in that two cell
Keep move on
Column 4 , {6,8}only can be in that two cell
Remaining number 2,3, 9
Ok , we got that 2!

[5] Continues fill in 1,2 that possible

[6] {7,9} only can be in row7 for cell 9
We only can put 9 for R7C9
As if we put 7 then  will not have 7 in cell 3

[7] continues fill in 7,9
R2C9 only have 3 to fill in(got 7,4 in that row)

[8] 8 only can be in R4C1,
And 1 only can be in R4C2

[9] fill in 1, 2,5 ,8
Then 4 etc...

Have fun!