Bring Down the Sky Grading Server
시간 제한4초메모리 제한1024 MB
각 시나리오에서 해커와 의장이 최선을 다해 싸울 때 해커가 서버의 연산력을 0 이하로 떨어뜨릴 수 있는지 판정한다.
문제
Despite running low on oil, the opening ceremony was a great success.* Now, the committee is looking forward to the first competition day. But what’s this? The chairman of the Technical Committee noticed some suspicious network activity—apparently someone is planning to hack the grading server!
The grading server possesses a specific computing power which the mysterious hacker will try to reduce to (or below) . But the server is also protected by firewalls, each of which will reduce the impact of any attack by a fixed amount . At each point in time, the hacker can now decide to either
- take down one of these firewalls, permanently reducing by (down to a minimum of ), or
- use all of their own computing power to attack the server, permanently reducing by .
However, the chairman can strike back by either taking down one of the hacker’s firewalls or by using the grading server’s computing power to attack the hacker, which will similarly reduce by . The chairman and the hacker take turns in their actions, with the hacker going first.
The committee will not know how much computing power and how many firewalls the hacker possesses until the hack has started. At the same time, because the committee might still be able to upgrade the server, its computing power and the number of its firewalls are also still unknown. To plan their defense, the committee therefore needs a program that tells them for different scenarios whether the hacker can bring down the grading server even if the chairman makes optimal decisions.
* At least if one ignores the grand finale with the stage collapsing under the weight of performers.
입력
The first line of the input contains the integers and . Then lines follow, each of which describes a scenario as above and consists of four integers : the computing power and number of firewalls of the mysterious hacker and of the grading server, respectively.
출력
Your program should output lines, each of which should consist of a single string: YES if the hacker can reduce the grading server’s computing power to or below in the corresponding scenario (regardless of the chairman’s actions), and NO otherwise.
힌트
Consider the first scenario of the first example:
- In the beginning, the hacker can attack the grading server, reducing by to a new value of .
- Afterwards, the chairman cannot reduce the hacker’s computing power by attacking, so the only sensible thing for him to do is to take down the hacker’s unique firewall.
- However, the hacker can then reduce the computing power of the grading server to by another attack, bringing down the server and ruining the first competition day.
In the second scenario on the other hand:
- Initially, the only thing the hacker can do is to take down one of the firewalls.
- Afterwards, the chairman can attack the hacker, reducing their computing power to .
- In the next two rounds, the hacker again can only take down one of the firewalls, while the chairman can attack each time, thus reducing below and successfully fighting off the hacker’s attempt.