Submission #3008297

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Source Code Expand

#[allow(unused_imports)]
use std::cmp::*;
#[allow(unused_imports)]
use std::collections::*;
use std::io::{Read, Write, BufWriter};
#[allow(dead_code)]
fn getline() -> String {
    let mut ret = String::new();
    std::io::stdin().read_line(&mut ret).ok().unwrap();
    ret
}
fn get_word() -> String {
    let mut stdin = std::io::stdin();
    let mut u8b: [u8; 1] = [0];
    loop {
        let mut buf: Vec<u8> = Vec::with_capacity(16);
        loop {
            let res = stdin.read(&mut u8b);
            if res.unwrap_or(0) == 0 || u8b[0] <= b' ' {
                break;
            } else {
                buf.push(u8b[0]);
            }
        }
        if buf.len() >= 1 {
            let ret = String::from_utf8(buf).unwrap();
            return ret;
        }
    }
}

#[allow(dead_code)]
fn get<T: std::str::FromStr>() -> T { get_word().parse().ok().unwrap() }

const MOD: i64 = 1_000_000_007;

/// Refers to external ::MOD.
/// Verified by: https://beta.atcoder.jp/contests/arc099/submissions/2893648
mod mod_int {
    use ::MOD;
    use std::ops::*;
    #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, PartialOrd, Ord)]
    pub struct ModInt { pub x: i64 }
    impl ModInt {
        fn check_integrity(self) {
            debug_assert!(self.x >= 0);
            debug_assert!(self.x < MOD);
        }
        // x >= 0
        pub fn new<T: Into<i64>>(x: T) -> Self { ModInt { x: x.into() % MOD } }
        #[allow(dead_code)]
        pub fn mul_fast(self, other: Self) -> Self {
            self.check_integrity();
            other.check_integrity();
            ModInt { x: self.x * other.x % MOD }
        }
        #[allow(dead_code)]
        pub fn mul_slow(self, other: Self) -> Self {
            // Naive multiplication in order to avoid overflow
            self.check_integrity();
            other.check_integrity();
            let mut sum = ModInt::new(0);
            let mut cur = self;
            let mut e = other.x;
            if self.x < other.x {
                cur = other;
                e = self.x;
            }
            while e > 0 {
                if e % 2 == 1 {
                    sum = sum + cur;
                }
                cur = cur + cur;
                e /= 2;
            }
            sum
        }
        pub fn pow(self, mut e: i64) -> Self {
            self.check_integrity();
            debug_assert!(e >= 0);
            let mut sum = ModInt::new(1);
            let mut cur = ModInt::new(self.x);
            while e > 0 {
                if e % 2 != 0 {
                    sum = sum * cur;
                }
                cur = cur * cur;
                e /= 2;
            }
            sum
        }
        pub fn inv(self) -> Self { self.pow(MOD - 2) }
    }
    impl Add for ModInt {
        type Output = Self;
        fn add(self, other: Self) -> Self {
            self.check_integrity();
            other.check_integrity();
            let mut sum = self.x + other.x;
            if sum >= MOD { sum -= MOD; }
            ModInt { x: sum }
        }
    }
    impl Sub for ModInt {
        type Output = Self;
        fn sub(self, other: Self) -> Self {
            self.check_integrity();
            other.check_integrity();
            let mut sum = self.x - other.x;
            if sum < 0 { sum += MOD; }
            ModInt { x: sum }
        }
    }
    impl Mul for ModInt {
        type Output = Self;
        fn mul(self, other: Self) -> Self {
            self.mul_fast(other)
        }
    }
    impl AddAssign for ModInt {
        fn add_assign(&mut self, rhs: ModInt) { *self = *self + rhs; }
    }
    impl SubAssign for ModInt {
        fn sub_assign(&mut self, rhs: ModInt) { *self = *self - rhs; }
    }
    impl MulAssign for ModInt {
        fn mul_assign(&mut self, rhs: ModInt) { *self = *self * rhs; }
    }
    impl ::std::fmt::Display for ModInt {
        fn fmt(&self, f: &mut::std::fmt::Formatter) -> ::std::fmt::Result {
            self.x.fmt(f)
        }
    }
} // mod mod_int
use mod_int::*;

fn solve() {
    let out = std::io::stdout();
    let mut out = BufWriter::new(out.lock());
    macro_rules! puts {
        ($format:expr) => (write!(out,$format).unwrap());
        ($format:expr, $($args:expr),+) => (write!(out,$format,$($args),*).unwrap())
    }
    let n = get();
    let m = get();
    let q = get();
    let a: Vec<usize> = (0 .. n).map(|_| get()).collect();
    let mut dp = vec![ModInt::new(0); m + 1];
    dp[0] = ModInt::new(1);
    for i in 0 .. n {
        let mut dp2 = vec![ModInt::new(0); m + 1];
        for j in 0 .. m + 1 {
            dp2[j] += dp[j];
            if j + a[i] + 1 <= m {
                dp2[j + a[i] + 1] -= dp[j];
            }
        }
        for j in 0 .. m {
            dp2[j + 1] += dp2[j];
        }
        dp = dp2;
    }
    let mut tbl = vec![vec![ModInt::new(0); m + 1]; n];
    for i in 0 .. n {
        let mut dp = dp.clone();
        for j in (0 .. m).rev() {
            dp[j + 1] -= dp[j];
        }
        for j in 0 .. m - a[i] {
            dp[j + a[i] + 1] += dp[j];
        }
        for j in 0 .. m + 1 { tbl[i][j] = dp[j]; }
    }
    for _ in 0 .. q {
        let k: usize = get::<usize>() - 1;
        let x: usize = get();
        puts!("{}\n", tbl[k][m - x]);
    }
}

fn main() {
    // In order to avoid potential stack overflow, spawn a new thread.
    let stack_size = 104_857_600; // 100 MB
    let thd = std::thread::Builder::new().stack_size(stack_size);
    thd.spawn(|| solve()).unwrap().join().unwrap();
}

Submission Info

Compile Error

warning: method is never used: `pow`, #[warn(dead_code)] on by default
  --> ./Main.rs:78:9
   |
78 |         pub fn pow(self, mut e: i64) -> Self {
   |         ^

warning: method is never used: `inv`, #[warn(dead_code)] on by default
  --> ./Main.rs:92:9
   |
92 |         pub fn inv(self) -> Self { self.pow(MOD - 2) }
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Judge Result