a_kawashiro https://blog.hatena.ne.jp/a_kawashiro/ a_kawashiroのブログ https://a-kawashiro.hatenablog.com/ topcoder 桁ごとに考えて足すだけ。 typedef long long LL; LL S(LL num) { num++; LL r=0; for(LL digit=0,i=10;digit<15;digit++,i*=10) { LL l=num; r+=l/i*45*(i/10); l%=i; for(LL j=0;0<l;j++,l-=(i/10)) r+=((i/10)<=l)?j*(i/10):j*l; } return r; } class SumThemAll { public: long long getSum(int lowerBound, int upperBound) { retu… 190 <iframe src="https://hatenablog-parts.com/embed?url=https%3A%2F%2Fa-kawashiro.hatenablog.com%2Fentry%2F20110411%2F1302522630" title="SRM311 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 2011-04-11 20:50:30 rich https://a-kawashiro.hatenablog.com/entry/20110411/1302522630 1.0 100%