此题是 2018 年 ICPC Asia Beijing Regional Contest 的 C 题. 题目大意 求斜边长度不超过 $n$($ n \le 10^9$) 的勾股数的数量.不计两直角边的顺序,即勾股数 (a, b, c) 和 (b, a, c) 视作同一组. 分析 这是一道颇为经典的计数问题. 请先阅读维基百科上的 Pythagorean triple 条目. 设斜边为 $n$ 的勾股数有 $f(n)$ 个.又设斜边为 $n$ 的本原勾股数有 $g(n)$ 个.于是有 $ f(n…

Pythagorean Triples 题目链接: http://codeforces.com/contest/707/problem/C Description Katya studies in a fifth grade. Recently her class studied right triangles and the Pythagorean theorem. It appeared, that there are triples of positive integers such th…

Pythagorean Triples time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Katya studies in a fifth grade. Recently her class studied right triangles and the Pythagorean theorem. It appeared, that…

C. Pythagorean Triples time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Katya studies in a fifth grade. Recently her class studied right triangles and the Pythagorean theorem. It appeared, t…

Katya studies in a fifth grade. Recently her class studied right triangles and the Pythagorean theorem. It appeared, that there are triples of positive integers such that you can construct a right triangle with segments of lengths corresponding to tr…

C. Pythagorean Triples 题目连接: http://www.codeforces.com/contest/707/problem/C Description Katya studies in a fifth grade. Recently her class studied right triangles and the Pythagorean theorem. It appeared, that there are triples of positive integers…

Description Katya studies in a fifth grade. Recently her class studied right triangles and the Pythagorean theorem. It appeared, that there are triples of positive integers such that you can construct a right triangle with segments of lengths corresp…

Description Katya studies in a fifth grade. Recently her class studied right triangles and the Pythagorean theorem. It appeared, that there are triples of positive integers such that you can construct a right triangle with segments of lengths corresp…

题目链接: C. Pythagorean Triples time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Katya studies in a fifth grade. Recently her class studied right triangles and the Pythagorean theorem. It appea…

Description Katya studies in a fifth grade. Recently her class studied right triangles and the Pythagorean theorem. It appeared, that there are triples of positive integers such that you can construct a right triangle with segments of lengths corresp…