a_kawashiro https://blog.hatena.ne.jp/a_kawashiro/ a_kawashiroのブログ https://a-kawashiro.hatenablog.com/ topcoder ACRushさすが。 #include <set> #include <vector> typedef long long LL; using namespace std; class ConstructBST { public: int n; LL ans; LL C[30][30]; set<int> se; int rec(int pos) { if(se.find(pos)==se.end()) return 0; else { int left=rec(pos*2); int right=rec(pos*2+1); ans*=C[left][right]; return left+1… 190 <iframe src="https://hatenablog-parts.com/embed?url=https%3A%2F%2Fa-kawashiro.hatenablog.com%2Fentry%2F20110424%2F1303639848" title="SRM319 div1 medium - 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> Hatena Blog https://hatena.blog 2011-04-24 19:10:48 rich https://a-kawashiro.hatenablog.com/entry/20110424/1303639848 1.0 100%