Since the solution is allways a relatively small number the simple brute force greedy solution works.
I implemented it after did not getting the dp solutions right… one can see the fragments in my code.
https://www.codechef.com/viewsolution/27683718
You can just try every value of N up to 1’000’000, and keep track of the highest, like I did 
I have done exactly same
What a way to avoid plagiarism. Copy someone’s code, introduce unnecessary variables like sid, momo, chale_chalo and you are done.
what is sid & momo tho…?
bro my idea is similar to yours and a used the fact that maximum count of digit 2-8 are 5
but why is my code partially correct CodeChef: Practical coding for everyone
when i precalculate 5 digits but when i precalculate upto 6 digits that its getting accepted see CodeChef: Practical coding for everyone
This solution fails on the testcase:
1
957520
Edit:
Actually, both of your solutions do - weak testcases causes the latter to get AC, I suppose 
oh thanks actually this is not my solution i was just going through the successful submissions and i wanted to find the idea behind this one (cause it looked simple XD),
and i tweaked it a little bit , is this one CodeChef: Practical coding for everyone getting correct??, this is the original one
That gets the correct answer for that particular testcase, at least - it’s far too slow to do an exhaustive check, though 
okay thanks
If anyone’s interested, here’s a program that exhaustively computes the results for all 1 \le N \le 1000000; because of the large size of the output, I use a simple compression scheme: the code -
1xA+B
means “write out the digit 1 A times, then write out B” (NB: B will be empty if N is square).
Sample (the last 10 entries):
N: 999991 leading-1's-compressed-result: 1x999988+222 sum: 1000000( = 1000 x 1000)
N: 999992 leading-1's-compressed-result: 1x999991+3 sum: 1000000( = 1000 x 1000)
N: 999993 leading-1's-compressed-result: 1x999967+39999999999999999999999999 sum: 1002001( = 1001 x 1001)
N: 999994 leading-1's-compressed-result: 1x999992+22 sum: 1000000( = 1000 x 1000)
N: 999995 leading-1's-compressed-result: 1x999968+229999999999999999999999999 sum: 1002001( = 1001 x 1001)
N: 999996 leading-1's-compressed-result: 1x999969+378889999999999999999999999 sum: 1002001( = 1001 x 1001)
N: 999997 leading-1's-compressed-result: 1x999996+2 sum: 1000000( = 1000 x 1000)
N: 999998 leading-1's-compressed-result: 1x999972+29999999999999999999999999 sum: 1002001( = 1001 x 1001)
N: 999999 leading-1's-compressed-result: 1x999972+277899999999999999999999999 sum: 1002001( = 1001 x 1001)
N: 1000000 leading-1's-compressed-result: 1x1000000+ sum: 1000000( = 1000 x 1000)
Takes about a second or so to process all 1000000 values, though the 86MB of output takes a few seconds longer 
Subtask-2, task-10 probably has the case where output is -1, but not sure
In given constrain there is no any number which output is -1.
Can you please elaborate this? How is it 27 by inspection?
What kind of inspection did you do? About that non-one digit thing as 27…please clarify
What is a dp array?
thanks man !!
could you explain what u have done…