a_kawashiro https://blog.hatena.ne.jp/a_kawashiro/ a_kawashiroのブログ https://a-kawashiro.hatenablog.com/ topcoder 難しい。分からん。 if(happiness[now]==-3) return now; でなんで-3なのかの自分なりのイメージ図。 #include <algorithm> #include <cstring> #define LIMIT 5000000 typedef long long LL; using namespace std; class ExtendedHappyNumbers { public: int K; int happiness[LIMIT]; int rec(int now) { if(0<happiness[now]) return happiness[now];… 190 <iframe src="https://hatenablog-parts.com/embed?url=https%3A%2F%2Fa-kawashiro.hatenablog.com%2Fentry%2F20110402%2F1301724600" title="SRM334 div2 hard - a_kawashiroのブログ" class="embed-card embed-blogcard" scrolling="no" frameborder="0" style="display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;"></iframe> http://cdn-ak.f.st-hatena.com/images/fotolife/a/a_kawashiro/20110402/20110402150912.gif Hatena Blog https://hatena.blog 2011-04-02 15:10:00 rich https://a-kawashiro.hatenablog.com/entry/20110402/1301724600 1.0 100%