Is the test cases weak in COKE2 of LTIME75?

Problem Link

My solution

I have used segment tree for range minimum query. And for each of the query I choose the actual range of cans which can be choosen. I got 70 points and WA in one of the test cases of 30 points.

So, is the test cases weak for the second subpart or I have missed something ?

Happens with me many times(but not for this one). For our luck, codechef does not include the smaller testcases with the bigger testcases