{"url":"https://sugarknri.hatenablog.com/entry/2016/04/10/085221","height":"190","type":"rich","description":"\u554f\u984c\u306f\u3053\u3061\u3089 No.71 \u305d\u308d\u3070\u3093 - yukicoderN\u500b\u306e\u3046\u3061k\u500b\u3092\u4e0a\u306e\u73e0\u3068\u3057\u3066\u6271\u3046\u3068 \u4e0a\u306e\u73e0\u306e\u72b6\u614b\u306fk+1\u901a\u308a \u4e0b\u306e\u73e0\u306e\u72b6\u614b\u306f(N-k)+1\u901a\u308a\u306a\u306e\u3067 \u6271\u3048\u308b\u6700\u5927\u306e\u5024\u306f(k+1)(N-k+1)-1\u3068\u306a\u308b \u3068\u3053\u308d\u3067\u3053\u308c\u306f\u3001\u548c\u304c\u4e00\u5b9a\u306e2\u6570\u306e\u7a4d\u3092\u6700\u5927\u5316\u3059\u308b\u554f\u984c\u306a\u306e\u3067\u30012\u6570\u304c\u8fd1\u304f\u306a\u308b\u3088\u3046\u306b\u3059\u308c\u3070\u826f\u3044 \uff08\u2235ab=((a+b)^2-(a-b)^2)/4\uff09 \u3088\u3063\u3066k=floor(N/2)\u3068\u3057\u305f\u3068\u304d\u306e\u5024\u304c\u6c42\u3081\u308b\u7b54\u3048 int main(){ int n; scanf(\"%d\",&n); printf(\"%ld\",1L*(n/2+1)*(n-n/2+1)-1); return 0; } \u3053\u306e\u7d50\u679c\u306f N\u304c\u5076\u2026","version":"1.0","author_url":"https://blog.hatena.ne.jp/sugarknri/","published":"2016-04-10 08:52:21","provider_name":"Hatena Blog","author_name":"sugarknri","width":"100%","title":"yukicoder No.71 \u305d\u308d\u3070\u3093","image_url":null,"blog_url":"https://sugarknri.hatenablog.com/","categories":[],"blog_title":"\u30e1\u30e2","html":"<iframe src=\"https://hatenablog-parts.com/embed?url=https%3A%2F%2Fsugarknri.hatenablog.com%2Fentry%2F2016%2F04%2F10%2F085221\" title=\"yukicoder No.71 \u305d\u308d\u3070\u3093 - \u30e1\u30e2\" class=\"embed-card embed-blogcard\" scrolling=\"no\" frameborder=\"0\" style=\"display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;\"></iframe>","provider_url":"https://hatena.blog"}