interview street challenge update

Solved string reduction. Now have 7.

Claire gave a very simple solution which also has a simple proof of correctness. Keep working on char with max cnt and another neighboring char until no more operation is possible. You must be left with 1 or 2 equal char. My solution is much more complicated and I do not have a good proof so far.

Your rank: 71
Your score: 460.625

Jan 6 update: hacked the bipartite matching code a bit and had 2 more testcases passed for problem solving problem.
Your rank: 66
Your score: 479.625

Jan 7 update: one more problem AC, string transmission. enumerate all periods and some simple DP with memorization.

Your rank: 63
Your score: 513.5

It gets harder to move up in rank now.

Jan 08 update
Had 2/10 for circle summation. Why TLE.
After 3 TLE, lost all 6pt earned for this problem. Back to 63.

solved circle summation, need O(N^2 logM) where N=50, M=10^9
Your rank: 61
Your score: 526
Rank Hacker Country Score Submissions Solved
61 lantimilan NA 526.00 36 9

Solved Equations, the answer is derived by x*y/(x+y)=N! and then ans is the number of factors of N!^2.
EQUATIONS C++
Submission Accepted
15/15 testcases passed
45 Point(s)
View Submission Processed 2012-01-09 01:22 UTC

Lego blocks: A simple DP problem, I don't know why I didn't solve it earlier.

Lego Blocks C++
Submission Accepted
10/10 testcases passed
50 Point(s)
View Submission Processed 2012-01-09 05:42 UTC

Now has 11. The remaining problems would be tough.