inamori https://blog.hatena.ne.jp/inamori/ inamori’s diary https://inamori.hateblo.jp/ https://atcoder.jp/contests/abc453/tasks/abc453_c1回ずつ再帰的に進めばの計算量ですが、時間がギリギリです。 v <- scan("stdin", integer()) N <- v[1] L <- v[2:(N+1)] F <- function(L, i, x) { if(i == N + 1) { return(0) } x1 <- x + L[i] # 正方向に進む n1 <- F(L, i+1, x1) if(x < 0 && 0 < x1) { n1 <- n1 + 1 } x2 <- x - L[i] n2 <- F(L, i+1,… 190 <iframe src="https://hatenablog-parts.com/embed?url=https%3A%2F%2Finamori.hateblo.jp%2Fentry%2F2026%2F04%2F17%2F210153" title="AtCoder Beginner Contest 453 C - inamori’s diary" 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 2026-04-17 21:01:53 rich https://inamori.hateblo.jp/entry/2026/04/17/210153 1.0 100%