#1029737 (Rust) No.2979 直角三角形の個数

• 問題: No.2979 直角三角形の個数
• ユーザー: akakimidori
• 提出日時: 2024-12-03 08:23:49
• 言語: Rust (1.83.0 + proconio)
• 結果: AC
• 実行時間: 3,092 ms / 4,000 ms
• コード長: 6,061 bytes
• コンパイル時間: 13,888 ms
• コンパイル使用メモリ: 380,040 KB
• 実行使用メモリ: 17,664 KB
• 最終ジャッジ日時: 2024-12-03 08:24:16
• 合計ジャッジ時間: 23,435 ms
• ジャッジサーバーID （参考情報）: judge4 / judge5

入力	結果	実行時間; 実行使用メモリ
testcase_00	AC	26 ms; 17,536 KB
testcase_01	AC	25 ms; 17,536 KB
testcase_02	AC	24 ms; 17,408 KB
testcase_03	AC	24 ms; 17,664 KB
testcase_04	AC	23 ms; 17,536 KB
testcase_05	AC	24 ms; 17,536 KB
testcase_06	AC	25 ms; 17,536 KB
testcase_07	AC	24 ms; 17,536 KB
testcase_08	AC	25 ms; 17,536 KB
testcase_09	AC	32 ms; 17,536 KB
testcase_10	AC	25 ms; 17,536 KB
testcase_11	AC	24 ms; 17,536 KB
testcase_12	AC	24 ms; 17,408 KB
testcase_13	AC	25 ms; 17,536 KB
testcase_14	AC	28 ms; 17,536 KB
testcase_15	AC	29 ms; 17,536 KB
testcase_16	AC	34 ms; 17,536 KB
testcase_17	AC	53 ms; 17,536 KB
testcase_18	AC	107 ms; 17,536 KB
testcase_19	AC	134 ms; 17,536 KB
testcase_20	AC	330 ms; 17,536 KB
testcase_21	AC	484 ms; 17,536 KB
testcase_22	AC	2,486 ms; 17,664 KB
testcase_23	AC	2,565 ms; 17,664 KB
testcase_24	AC	27 ms; 17,536 KB
testcase_25	AC	26 ms; 17,408 KB
testcase_26	AC	35 ms; 17,536 KB
testcase_27	AC	26 ms; 17,536 KB
testcase_28	AC	3,092 ms; 17,664 KB

コンパイルメッセージ

warning: unused variable: `ans`
  --> src/main.rs:81:13
   |
81 |     let mut ans = 0;
   |             ^^^ help: if this is intentional, prefix it with an underscore: `_ans`
   |
   = note: `#[warn(unused_variables)]` on by default

warning: variable does not need to be mutable
  --> src/main.rs:81:9
   |
81 |     let mut ans = 0;
   |         ----^^^
   |         |
   |         help: remove this `mut`
   |
   = note: `#[warn(unused_mut)]` on by default

warning: function `test` is never used
  --> src/main.rs:77:4
   |
77 | fn test() {
   |    ^^^^
   |
   = note: `#[warn(dead_code)]` on by default

ソースコード

// m^2-n^2, 2mn, m^2+n^2
// m>n
// m, nは互いに素かつ偶奇が違う
// 2m(m+n)
//
// N/(2km(m+n))
// の総和
//
// 1 <= n <= m-1 について商列挙っぽいことするとどうなる？
// N=L の時Qとして
// Q = N/(2m(m+n))
// m+n= N/(2mQ)
// n=N/(2mQ)-m
// 4secならギリギリ間に合うか？

fn main() {
    input!(n: usize);
    let sieve = Sieve::new(2000000);
    let mut p = vec![];
    let mut a = vec![];
    let mut ans = 0;
    for m in 2.. {
        if 2 * m * (m + 1) > n {
            break;
        }
        a.clear();
        let up = (m - 1).min(n / (2 * m) - m);
        let mut l = 1;
        while l <= up {
            let q = n / (2 * m * (m + l));
            let r = n / (2 * m * q) - m;
            a.push((l as u32 - 1, r.min(up) as u32, q));
            l = r + 1;
        }
        sieve.factorize(m, &mut p);
        if m % 2 == 0 {
            for (i, &f) in p.iter().enumerate() {
                let f = f as u32;
                let mut pre = 0;
                if i.count_ones() % 2 == 0 {
                    for &(_, r, q) in a.iter().filter(|p| f <= p.1) {
                        let u = r / f;
                        ans += q * (u - pre) as usize;
                        pre = u;
                    }
                } else {
                    for &(_, r, q) in a.iter().filter(|p| f <= p.1) {
                        let u = r / f;
                        ans -= q * (u - pre) as usize;
                        pre = u;
                    }
                }
            }
        } else {
            for (i, f) in p.iter().enumerate() {
                let f = *f as u32 * 2;
                let mut pre = 0;
                if i.count_ones() % 2 == 0 {
                    for &(_, r, q) in a.iter().filter(|p| f <= p.1) {
                        let u = r / f;
                        ans += q * (u - pre) as usize;
                        pre = u;
                    }
                } else {
                    for &(_, r, q) in a.iter().filter(|p| f <= p.1) {
                        let u = r / f;
                        ans -= q * (u - pre) as usize;
                        pre = u;
                    }
                }
            }
        }
    }
    println!("{ans}");
}

fn test() {
    let n = 10usize.pow(12);
    let sieve = Sieve::new(2000000);
    let mut p = vec![];
    let mut ans = 0;
    let mut sum = 0;
    for m in 2.. {
        if 2 * m * (m + 1) > n {
            break;
        }
        let mut l = 1;
        let mut c = 0;
        while l <= m - 1 {
            let q = n / (2 * m * (m + l));
            let r = n / (2 * m * q);
            l = r + 1;
            c += 1;
        }
        p.clear();
        sieve.factorize(m, &mut p);
        sum += c * p.len();
        /*
        if m % 2 == 0 {
            let up = (m - 1).min(n / (2 * m) - m);
            for (i, f) in p.iter().enumerate() {
                if i.count_ones() % 2 == 0 {
                    ans += up / *f;
                } else {
                    ans -= up / *f;
                }
            }
        } else {
            let up = (m - 1).min(n / (2 * m) - m) / 2;
            for (i, f) in p.iter().enumerate() {
                if i.count_ones() % 2 == 0 {
                    ans += up / *f;
                } else {
                    ans -= up / *f;
                }
            }
        }
        */
    }
    println!("{}", sum);
}

// ---------- begin input macro ----------
// reference: https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
#[macro_export]
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

#[macro_export]
macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};
    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

#[macro_export]
macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };
    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };
    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };
    ($iter:expr, bytes) => {
        read_value!($iter, String).bytes().collect::<Vec<u8>>()
    };
    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };
    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}
// ---------- end input macro ----------
// --------- end sieve ----------
pub struct Sieve {
    size: usize,
    factor: Vec<usize>,
}

impl Sieve {
    pub fn new(size: usize) -> Sieve {
        let mut factor = (0..(size + 1)).collect::<Vec<_>>();
        for i in (2..).take_while(|p| p * p <= size) {
            if i == factor[i] {
                for j in i..(size / i + 1) {
                    factor[j * i] = i;
                }
            }
        }
        Sieve {
            size: size,
            factor: factor,
        }
    }
    pub fn factor(&self, n: usize) -> Option<usize> {
        assert!(n <= self.size);
        if n == 1 {
            None
        } else {
            Some(self.factor[n])
        }
    }
    pub fn factorize(&self, mut n: usize, res: &mut Vec<usize>) {
        assert!(n <= self.size);
        res.clear();
        res.push(1);
        while let Some(p) = self.factor(n) {
            let len = res.len();
            while n % p == 0 {
                n /= p;
            }
            for _ in 0..len {
                let v = res[res.len() - len] * p;
                res.push(v);
            }
        }
    }
}
// --------- end sieve ----------