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
