그리디 알고리즘
https://www.acmicpc.net/problem/13305

정수론 및 조합론
https://www.acmicpc.net/problem/5086
https://www.acmicpc.net/problem/1037
https://www.acmicpc.net/problem/2609
https://www.acmicpc.net/problem/1934
https://www.acmicpc.net/problem/2981