#1011435 (Rust) No.864 四方演算

• 問題: No.864 四方演算
• ユーザー: Yukino DX.
• 提出日時: 2024-09-18 23:15:56
• 言語: Rust (1.77.0 + proconio)
• 結果: AC
• 実行時間: 10 ms / 1,000 ms
• コード長: 3,285 bytes
• コンパイル時間: 13,724 ms
• コンパイル使用メモリ: 383,748 KB
• 実行使用メモリ: 6,944 KB
• 最終ジャッジ日時: 2024-09-18 23:16:12
• 合計ジャッジ時間: 15,084 ms
• ジャッジサーバーID （参考情報）: judge1 / judge3

入力	結果	実行時間; 実行使用メモリ
testcase_00	AC	1 ms; 6,812 KB
testcase_01	AC	10 ms; 6,940 KB
testcase_02	AC	7 ms; 6,940 KB
testcase_03	AC	7 ms; 6,944 KB
testcase_04	AC	9 ms; 6,940 KB
testcase_05	AC	5 ms; 6,944 KB
testcase_06	AC	8 ms; 6,940 KB
testcase_07	AC	8 ms; 6,944 KB
testcase_08	AC	6 ms; 6,944 KB
testcase_09	AC	4 ms; 6,940 KB
testcase_10	AC	4 ms; 6,940 KB
testcase_11	AC	3 ms; 6,940 KB
testcase_12	AC	7 ms; 6,944 KB
testcase_13	AC	5 ms; 6,944 KB
testcase_14	AC	2 ms; 6,944 KB
testcase_15	AC	10 ms; 6,944 KB
testcase_16	AC	7 ms; 6,940 KB
testcase_17	AC	8 ms; 6,940 KB
testcase_18	AC	7 ms; 6,944 KB
testcase_19	AC	6 ms; 6,944 KB
testcase_20	AC	9 ms; 6,940 KB
testcase_21	AC	7 ms; 6,940 KB
testcase_22	AC	7 ms; 6,944 KB
testcase_23	AC	2 ms; 6,940 KB
testcase_24	AC	5 ms; 6,944 KB
testcase_25	AC	4 ms; 6,944 KB
testcase_26	AC	6 ms; 6,940 KB
testcase_27	AC	1 ms; 6,940 KB
testcase_28	AC	0 ms; 6,944 KB
testcase_29	AC	1 ms; 6,940 KB

ソースコード

use proconio::input;

fn main() {
    input! {
        n:usize,
        k:usize,
    }

    let divs_k = divisors(k);
    let mut ans = 0;
    for &div_k in divs_k.iter() {
        let (a, b) = (div_k, k / div_k);
        let c1 = (n.min(a - 1) as i64 - a.saturating_sub(n).max(1) as i64 + 1).max(0);
        let c2 = (n.min(b - 1) as i64 - b.saturating_sub(n).max(1) as i64 + 1).max(0);
        ans += c1 * c2;
    }

    println!("{}", ans);
}

use math::*;
mod math {
    #[allow(dead_code)]
    pub fn pow(mut n: usize, mut e: usize, m: usize) -> usize {
        let mut res = 1;
        n %= m;
        while 0 < e {
            if e & 1 != 0 {
                res *= n;
                res %= m;
            }

            n *= n;
            n %= m;
            e >>= 1;
        }

        res
    }

    #[allow(dead_code)]
    pub fn gcd(a: usize, b: usize) -> usize {
        if b == 0 {
            a
        } else {
            gcd(b, a % b)
        }
    }

    #[allow(dead_code)]
    pub fn lcm(a: usize, b: usize) -> usize {
        a / gcd(a, b) * b
    }

    #[allow(dead_code)]
    pub fn prime_factor(mut n: usize) -> std::collections::HashMap<usize, usize> {
        let mut pfacs = std::collections::HashMap::new();
        for d in 2.. {
            if d * d > n {
                break;
            }

            while n % d == 0 {
                *pfacs.entry(d).or_insert(0) += 1;
                n /= d;
            }
        }
        if n != 1 {
            *pfacs.entry(n).or_insert(0) += 1;
        }

        pfacs
    }

    #[allow(dead_code)]
    pub fn divisors(n: usize) -> Vec<usize> {
        let mut divs = vec![];
        for d in (1..).take_while(|&d| d * d <= n) {
            if n % d == 0 {
                divs.push(d);
                if n / d != d {
                    divs.push(n / d);
                }
            }
        }

        divs
    }

    #[allow(dead_code)]
    pub fn eratosthenes_sieve(n: usize) -> Vec<usize> {
        let mut is_primes = vec![true; n + 1];
        is_primes[0] = false;
        is_primes[1] = false;
        let mut primes = vec![];

        for i in 2..=n {
            if !is_primes[i] {
                continue;
            }

            for j in (2 * i..=n).step_by(i) {
                is_primes[j] = false;
            }
        }

        for (val, is_prime) in is_primes.into_iter().enumerate() {
            if is_prime {
                primes.push(val);
            }
        }

        primes
    }

    #[allow(dead_code)]
    pub fn base_n(mut base10: usize, base: usize, len: usize) -> Vec<usize> {
        let mut base_n = vec![];
        for _ in 0..len {
            base_n.push(base10 % base);
            base10 /= base;
        }
        base_n.reverse();

        base_n
    }

    #[allow(dead_code)]
    pub fn div_floor(mut a: i64, mut b: i64) -> i64 {
        if b < 0 {
            a = -a;
            b = -b;
        }

        if a >= 0 {
            a / b
        } else {
            (a + 1) / b - 1
        }
    }

    #[allow(dead_code)]
    pub fn div_ceil(mut a: i64, mut b: i64) -> i64 {
        if b < 0 {
            a = -a;
            b = -b;
        }
        if a > 0 {
            (a - 1) / b + 1
        } else {
            a / b
        }
    }
}