AtCoder Beginner Contest 334 D

https://atcoder.jp/contests/abc334/tasks/abc334_d

Rをソートして累積和を求めておいて二分探索ですね。

// Reindeer and Sleigh
#![allow(non_snake_case)]


//////////////////// library ////////////////////

fn read<T: std::str::FromStr>() -> T {
    let mut line = String::new();
    std::io::stdin().read_line(&mut line).ok();
    line.trim().parse().ok().unwrap()
}

fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>().split_whitespace()
            .map(|e| e.parse().ok().unwrap()).collect()
}


//////////////////// process ////////////////////

fn read_input() -> (usize, Vec<usize>) {
    let v = read_vec();
    let Q = v[1];
    let R = read_vec();
    (Q, R)
}

fn accumulate(mut R: Vec<usize>) -> Vec<usize> {
    R.sort();
    let mut A: Vec<usize> = vec![0; R.len()+1];
    for i in 0..R.len() {
        A[i+1] = A[i] + R[i]
    }
    A
}

fn bin_search(first: usize, last: usize, X: usize, A: &Vec<usize>) -> usize {
    if last - first == 1 {
        first
    }
    else {
        let mid = (first + last) / 2;
        if A[mid] <= X {
            bin_search(mid, last, X, A)
        }
        else {
            bin_search(first, mid, X, A)
        }
    }
}

fn F(Q: usize, R: Vec<usize>) {
    let A = accumulate(R);
    for _ in 0..Q {
        let X: usize = read();
        let n = bin_search(0, A.len(), X, &A);
        println!("{}", n)
    }
}

fn main() {
    let (Q, R) = read_input();
    F(Q, R)
}