An old blog discussed about how to ac every problem. One comment from a certain user struck me. Instead of the usual ~10^{-6736}~ chance, I can make it ~100\%~ under some conditions.

Conditions

These following conditions must be met in order to guess, no, actually get the tests:

• Being allowed to submit as many times as you want.
• No batch grading.
• Ability to use binary search.
• Patience.

Proccess

There is one trick I would like to introduce to you: the Kim Jong Un trick.

Code:

void nuke(){
    while (1){}
}

How does this work?

When you call the ~nuke()~ function, your code automatically gets TLE (Time Limit Exceeded).

So how do we use this to our advantage?

For instance, the input is only a positive integer ~n~ ~(1 \le n \le 1000)~. What you are going to do is binary search on ~n~. First, you set the left bound ~l~ to 1, and the right bound ~r~ to ~1000~. You set ~mid~ to ~(l + r)/2~. You read ~n~ from the input, check:

• If ~n < mid~, call the ~nuke()~ function.
• Else, don't call the function.

After that, submit your code and check if it gets TLE. If it does, it means that ~n < mid~, and you should set the right bound to ~mid - 1~, if it doesn't, you set the left bound to ~mid + 1~. After about ~10~ submissions, you will be able to guess n of ~1~ test.

Do note that it's manual binary search (you do it by hand), not regular binary search.

This also works with bigger input (~2+~ integers, a whole array, etc.). For instance, you are trying to guess tests of a problem in which input consists of an array. You guess ~n~ using the method above, and guess ~a_i~ for all ~1 \le i \le n~ using the same mentioned method. Though if the array is long (~10^6+~ elements), good luck with staying up all night to submit your code tens of millions of times.