Submission #1097636

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Source Code Expand

use std::io::{self, Stdin};
use std::str::{self, FromStr};
use std::error::Error;

fn main() {
    let mut sc = Scanner::new();
    let n: usize = sc.ne();
    let nn = n as i64;
    let a: Vec<i64> = (0..n).map(|_| sc.ne()).collect();
    let sum: i64 = a.iter().fold(0, |acc, &x| acc + x);
    let sumn: i64 = (1..nn + 1).fold(0, |acc, x| acc + x);
    let mut ok = true;
    if sum % sumn != 0 {
        ok = false;
    }
    let key = sum / sumn;
    let mut cntd = 0;
    for i in 0..n {
        let j = (i + 1) % n;
        let x = a[j] - a[i];
        match x {
            val if val == key => {}
            val if val > 0 => ok = false,
            _ => {
                let d = key - x;
                if d % nn != 0 {
                    ok = false;
                } else {
                    cntd += d / nn;
                }
            }
        }
    }
    if cntd != key {
        ok = false;
    }
    println!("{}", if ok { "YES" } else { "NO" });
}
struct Scanner {
    stdin: Stdin,
    id: usize,
    buf: Vec<u8>,
}

impl Scanner {
    fn new() -> Scanner {
        Scanner {
            stdin: io::stdin(),
            id: 0,
            buf: Vec::new(),
        }
    }
    fn next_line(&mut self) -> Option<String> {
        let mut res = String::new();
        match self.stdin.read_line(&mut res) {
            Ok(0) => return None,
            Ok(_) => Some(res),
            Err(why) => panic!("error in read_line: {}", why.description()),
        }
    }
    fn next<T: FromStr>(&mut self) -> Option<T> {
        while self.buf.len() == 0 {
            self.buf = match self.next_line() {
                Some(r) => {
                    self.id = 0;
                    r.trim().as_bytes().to_owned()
                }
                None => return None,
            };
        }
        let l = self.id;
        assert!(self.buf[l] != b' ');
        let n = self.buf.len();
        let mut r = l;
        while r < n && self.buf[r] != b' ' {
            r += 1;
        }
        let res = match str::from_utf8(&self.buf[l..r]).ok().unwrap().parse::<T>() {
            Ok(s) => Some(s),
            Err(_) => panic!("parse error"),
        };
        while r < n && self.buf[r] == b' ' {
            r += 1;
        }
        if r == n {
            self.buf.clear();
        } else {
            self.id = r;
        }
        res
    }
    fn ne<T: FromStr>(&mut self) -> T {
        self.next::<T>().unwrap()
    }
}

Submission Info

Judge Result