For this problem http://codeforces.com/problemset/problem/492/B. I've used a binary search approach to get a solution. However, I'm getting an incorrect result in the floating points for the answer. How can I overcome this.

This is my solution http://codeforces.com/contest/492/submission/17201833

http://codeforces.com/contest/257/problem/C

For the above problem I am getting a runtime error.

This is my submission http://codeforces.com/contest/257/submission/13480280

The test case is too large hence I am unable to debug it.