Problem:
RSQ and RUQ

Write a program which manipulates a sequence $A$ = {$a_0, a_1, ..., a_{n-1}$} with the following operations:

$update(s, t, x)$: change $a_s, a_{s+1}, ..., a_t$ to $x$.

$getSum(s, t)$: print the sum of $a_s, a_{s+1}, ..., a_t$.

Note that the initial values of $a_i ( i = 0, 1, ..., n-1 )$ are 0.

Input

$n$ $q$
$query_1$
$query_2$
:
$query_q$

In the first line, $n$ (the number of elements in $A$) and $q$ (the number of queries) are given. Then, $i$-th query $query_i$ is given in the following format:

0 $s$ $t$ $x$

or

1 $s$ $t$

The first digit represents the type of the query. '0' denotes $update(s, t, x)$
and '1' denotes $find(s, t)$.

Output

For each $getSum$ query, print the sum in a line.

Constraints

$1 ≤ n ≤ 100000$

$1 ≤ q ≤ 100000$

$0 ≤ s ≤ t < n$

$-1000 ≤ x ≤ 1000$

Sample Input 1

6 7
0 1 3 1
0 2 4 -2
1 0 5
1 0 1
0 3 5 3
1 3 4
1 0 5

Sample Output 1

-5
1
6
8

Solution in Rust (judge verdict: Accepted)

#[doc = " https://github.com/hatoo/competitive-rust-snippets"]
#[allow(unused_imports)]
use std::cmp::{max, min, Ordering};
#[allow(unused_imports)]
use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, VecDeque};
#[allow(unused_imports)]
use std::io::{stdin, stdout, BufWriter, Write};
#[allow(unused_imports)]
use std::iter::FromIterator;
#[allow(unused_macros)]
macro_rules ! debug { ( $ ( $ a : expr ) ,* ) => { eprintln ! ( concat ! ( $ ( stringify ! ( $ a ) , " = {:?}, " ) ,* ) , $ ( $ a ) ,* ) ; } }
#[macro_export]
macro_rules ! input { ( source = $ s : expr , $ ( $ r : tt ) * ) => { let mut parser = Parser :: from_str ( $ s ) ; input_inner ! { parser , $ ( $ r ) * } } ; ( parser = $ parser : ident , $ ( $ r : tt ) * ) => { input_inner ! { $ parser , $ ( $ r ) * } } ; ( new_stdin_parser = $ parser : ident , $ ( $ r : tt ) * ) => { let stdin = std :: io :: stdin ( ) ; let reader = std :: io :: BufReader :: new ( stdin . lock ( ) ) ; let mut $ parser = Parser :: new ( reader ) ; input_inner ! { $ parser , $ ( $ r ) * } } ; ( $ ( $ r : tt ) * ) => { input ! { new_stdin_parser = parser , $ ( $ r ) * } } ; }
#[macro_export]
macro_rules ! input_inner { ( $ parser : ident ) => { } ; ( $ parser : ident , ) => { } ; ( $ parser : ident , $ var : ident : $ t : tt $ ( $ r : tt ) * ) => { let $ var = read_value ! ( $ parser , $ t ) ; input_inner ! { $ parser $ ( $ r ) * } } ; }
#[macro_export]
macro_rules ! read_value { ( $ parser : ident , ( $ ( $ t : tt ) ,* ) ) => { ( $ ( read_value ! ( $ parser , $ t ) ) ,* ) } ; ( $ parser : ident , [ $ t : tt ; $ len : expr ] ) => { ( 0 ..$ len ) . map ( | _ | read_value ! ( $ parser , $ t ) ) . collect ::< Vec < _ >> ( ) } ; ( $ parser : ident , chars ) => { read_value ! ( $ parser , String ) . chars ( ) . collect ::< Vec < char >> ( ) } ; ( $ parser : ident , usize1 ) => { read_value ! ( $ parser , usize ) - 1 } ; ( $ parser : ident , $ t : ty ) => { $ parser . next ::<$ t > ( ) . expect ( "Parse error" ) } ; }
use std::io;
use std::io::BufRead;
use std::str;
pub struct Parser<R> {
    reader: R,
    buf: Vec<u8>,
    pos: usize,
}
impl Parser<io::Empty> {
    pub fn from_str(s: &str) -> Parser<io::Empty> {
        Parser {
            reader: io::empty(),
            buf: s.as_bytes().to_vec(),
            pos: 0,
        }
    }
}
impl<R: BufRead> Parser<R> {
    pub fn new(reader: R) -> Parser<R> {
        Parser {
            reader: reader,
            buf: vec![],
            pos: 0,
        }
    }
    pub fn update_buf(&mut self) {
        self.buf.clear();
        self.pos = 0;
        loop {
            let (len, complete) = {
                let buf2 = self.reader.fill_buf().unwrap();
                self.buf.extend_from_slice(buf2);
                let len = buf2.len();
                if len == 0 {
                    break;
                }
                (len, buf2[len - 1] <= 0x20)
            };
            self.reader.consume(len);
            if complete {
                break;
            }
        }
    }
    pub fn next<T: str::FromStr>(&mut self) -> Result<T, T::Err> {
        loop {
            let mut begin = self.pos;
            while begin < self.buf.len() && (self.buf[begin] <= 0x20) {
                begin += 1;
            }
            let mut end = begin;
            while end < self.buf.len() && (self.buf[end] > 0x20) {
                end += 1;
            }
            if begin != self.buf.len() {
                self.pos = end;
                return str::from_utf8(&self.buf[begin..end]).unwrap().parse::<T>();
            } else {
                self.update_buf();
            }
        }
    }
}
#[allow(unused_macros)]
macro_rules ! debug { ( $ ( $ a : expr ) ,* ) => { eprintln ! ( concat ! ( $ ( stringify ! ( $ a ) , " = {:?}, " ) ,* ) , $ ( $ a ) ,* ) ; } }
#[doc = " https://github.com/hatoo/competitive-rust-snippets"]
const BIG_STACK_SIZE: bool = true;
#[allow(dead_code)]
fn main() {
    use std::thread;
    if BIG_STACK_SIZE {
        thread::Builder::new()
            .stack_size(32 * 1024 * 1024)
            .name("solve".into())
            .spawn(solve)
            .unwrap()
            .join()
            .unwrap();
    } else {
        solve();
    }
}
trait SEGImpl {
    type Monoid: Copy;
    type OperatorMonoid: Copy + PartialEq;
    fn m0() -> Self::Monoid;
    fn om0() -> Self::OperatorMonoid;
    fn f(x: Self::Monoid, y: Self::Monoid) -> Self::Monoid;
    fn g(x: Self::Monoid, y: Self::OperatorMonoid, len: usize) -> Self::Monoid;
    fn h(x: Self::OperatorMonoid, y: Self::OperatorMonoid) -> Self::OperatorMonoid;
}
struct SEG<T: SEGImpl> {
    n: usize,
    data: Vec<T::Monoid>,
    lazy: Vec<T::OperatorMonoid>,
}
impl <T: SEGImpl> SEG<T> {
    fn new(init: T::Monoid, n: usize) -> SEG<T> {
        let mut m = 1;
        while m < n { m *= 2; }
        SEG {
            n: m,
            data: vec![init; m*2],
            lazy: vec![T::om0(); m*2],
        }
    }
    fn propagate(&mut self, k: usize, len: usize) {
        if self.lazy[k] != T::om0() {
            if k < self.n {
                self.lazy[2*k+0] = T::h(self.lazy[2*k+0], self.lazy[k]);
                self.lazy[2*k+1] = T::h(self.lazy[2*k+1], self.lazy[k]);
            }
            self.data[k] = T::g(self.data[k], self.lazy[k], len);
            self.lazy[k] = T::om0();
        }
    }
    fn do_update(&mut self, a: usize, b: usize, x: T::OperatorMonoid, k: usize, l: usize, r: usize) -> T::Monoid {
        self.propagate(k, r-l);
        if r <= a || b <= l {
            self.data[k]
        } else if a <= l && r <= b {
            self.lazy[k] = T::h(self.lazy[k], x);
            self.propagate(k, r-l);
            self.data[k]
        } else {
            self.data[k] = T::f(
                self.do_update(a, b, x, 2*k+0, l, (l+r)>>1),
                self.do_update(a, b, x, 2*k+1, (l+r)>>1, r)
            );
            self.data[k]
        }
    }
    fn update(&mut self, a: usize, b: usize, x: T::OperatorMonoid) -> T::Monoid {
        let n = self.n;
        self.do_update(a, b, x, 1, 0, n)
    }
    fn do_query(&mut self, a: usize, b: usize, k: usize, l: usize, r: usize) -> T::Monoid {
        self.propagate(k, r-l);
        if r <= a || b <= l {
            T::m0()
        } else if a <= l && r <= b {
            self.data[k]
        } else {
            T::f(
                self.do_query(a, b, 2*k+0, l, (l+r)>>1),
                self.do_query(a, b, 2*k+1, (l+r)>>1, r)
            )
        }
    }
    fn query(&mut self, a: usize, b: usize) -> T::Monoid {
        let n = self.n;
        self.do_query(a, b, 1, 0, n)
    }
}

struct RSQ_RUQ;
impl SEGImpl for RSQ_RUQ { 
    type Monoid = i64;
    type OperatorMonoid = i64;
    fn m0() -> Self::Monoid {
        0
    }
    fn om0() -> Self::OperatorMonoid {
        1<<40
    }
    fn f(x: Self::Monoid, y: Self::Monoid) -> Self::Monoid {
        x + y
    }
    fn g(x: Self::Monoid, y: Self::OperatorMonoid, len: usize) -> Self::Monoid {
        len as i64 * y
    }
    fn h(x: Self::OperatorMonoid, y: Self::OperatorMonoid) -> Self::OperatorMonoid {
        y
    }
}
fn solve() {
    input! {
        new_stdin_parser = parser,
        n: usize, q: usize,
    }

    let mut seg: SEG<RSQ_RUQ> = SEG::new(0, n);

    for _ in 0..q {
        input! {
            parser = parser,
            com: usize,
        }
        if com == 0 {
            input! {
                parser = parser,
                s: usize, t: usize, x: i64,
            }
            seg.update(s,t+1,x);
        } else {
            input! {
                parser = parser,
                i: usize, j: usize,
            }
            println!("{}", seg.query(i,j+1));
        }
    }
}