https://codeforces.me/contest/1345/submission/187186494 The general idea here is to simulate what is happening. You don’t actually need to check the heights of all h 1-10^9 but rather check all the heights that use less than or equal to 10^9 cards to create. Then you can binary search for the value or use a floor function for a given data structure to subtract the largest height you can build given the cards you have and repeat until your stack becomes less than 2. The key here is the height is not important, but rather how many cards necessary to build the height.