Problem:
RMQ and RUQ

Write a program which manipulates a sequence A = {a0, a1, . . . , an−1} with the following operations:

update(s, t, x): change as, as+1, ..., at to x.

find(s, t): report the minimum element in as, as+1, ..., at.

Note that the initial values of ai (i = 0, 1, . . . , n−1) are 231-1.

Input

n q
query1
query2
:
queryq

In the first line, n (the number of elements in A) and q (the number of queries) are given. Then, ith query queryi 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 find operation, print the minimum value.

Constraints

1 ≤ n ≤ 100000

1 ≤ q ≤ 100000

0 ≤ s ≤ t < n

0 ≤ x < 231−1

Sample Input 1

3 5
0 0 1 1
0 1 2 3
0 2 2 2
1 0 2
1 1 2

Sample Output 1

1
2

Sample Input 2

1 3
1 0 0
0 0 0 5
1 0 0

Sample Output 2

2147483647
5

Solution in Rust (judge verdict: Accepted)

#[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::iter::FromIterator;
#[allow(unused_imports)]
use std::io::{stdin, stdout, BufWriter, Write};
mod util {
    use std::io::stdin;
    use std::str::FromStr;
    use std::fmt::Debug;
    #[allow(dead_code)]
    pub fn line() -> String {
        let mut line: String = String::new();
        stdin().read_line(&mut line).unwrap();
        line.trim().to_string()
    }
    #[allow(dead_code)]
    pub fn gets<T: FromStr>() -> Vec<T>
    where
        <T as FromStr>::Err: Debug,
    {
        let mut line: String = String::new();
        stdin().read_line(&mut line).unwrap();
        line.split_whitespace()
            .map(|t| t.parse().unwrap())
            .collect()
    }
}
#[allow(unused_macros)]
macro_rules ! get { ( $ t : ty ) => { { let mut line : String = String :: new ( ) ; stdin ( ) . read_line ( & mut line ) . unwrap ( ) ; line . trim ( ) . parse ::<$ t > ( ) . unwrap ( ) } } ; ( $ ( $ t : ty ) ,* ) => { { let mut line : String = String :: new ( ) ; stdin ( ) . read_line ( & mut line ) . unwrap ( ) ; let mut iter = line . split_whitespace ( ) ; ( $ ( iter . next ( ) . unwrap ( ) . parse ::<$ t > ( ) . unwrap ( ) , ) * ) } } ; ( $ t : ty ; $ n : expr ) => { ( 0 ..$ n ) . map ( | _ | get ! ( $ t ) ) . collect ::< Vec < _ >> ( ) } ; ( $ ( $ t : ty ) ,*; $ n : expr ) => { ( 0 ..$ n ) . map ( | _ | get ! ( $ ( $ t ) ,* ) ) . collect ::< Vec < _ >> ( ) } ; ( $ t : ty ;; ) => { { let mut line : String = String :: new ( ) ; stdin ( ) . read_line ( & mut line ) . unwrap ( ) ; line . split_whitespace ( ) . map ( | t | t . parse ::<$ t > ( ) . unwrap ( ) ) . collect ::< Vec < _ >> ( ) } } ; }
#[allow(unused_macros)]
macro_rules ! debug { ( $ ( $ a : expr ) ,* ) => { println ! ( concat ! ( $ ( stringify ! ( $ a ) , " = {:?}, " ) ,* ) , $ ( $ a ) ,* ) ; } }

#[allow(dead_code)]
struct SEG<T: SEGimpl> {
    n: usize,
    buf: Vec<T::Elem>,
    phantom: std::marker::PhantomData<T>,
}
impl<T: SEGimpl> SEG<T> {
    #[allow(dead_code)]
    fn new(n: usize, init: T::Elem) -> SEG<T> {
        let n = (1..).map(|i| 1 << i).find(|&x| x >= n).unwrap();
        SEG {
            n: n,
            buf: vec![init; 2 * n],
            phantom: std::marker::PhantomData,
        }
    }
    #[allow(dead_code)]
    fn eval(&mut self, k: usize, l: usize, r: usize) {
        if r - l > 1 {
            let (l, r) = self.buf.split_at_mut(2 * k + 1);
            let (c1, c2) = r.split_at_mut(1);
            T::eval(&mut l[k], Some((&mut c1[0], &mut c2[0])));
        } else {
            T::eval(&mut self.buf[k], None);
        }
    }
    #[allow(dead_code)]
    fn r(&mut self, x: &T::A, a: usize, b: usize, k: usize, l: usize, r: usize) {
        self.eval(k, l, r);
        if r <= a || b <= l {
            return;
        }
        if a <= l && r <= b {
            T::range(x, &mut self.buf[k], l, r);
            self.eval(k, l, r);
            return;
        }
        self.r(x, a, b, 2 * k + 1, l, (l + r) / 2);
        self.r(x, a, b, 2 * k + 2, (l + r) / 2, r);
        let (l, r) = self.buf.split_at_mut(2 * k + 1);
        let (c1, c2) = r.split_at_mut(1);
        T::reduce(&mut l[k], &c1[0], &c2[0]);
    }
    #[allow(dead_code)]
    fn range_add(&mut self, x: &T::A, a: usize, b: usize) {
        let n = self.n;
        self.r(x, a, b, 0, 0, n);
    }
    #[allow(dead_code)]
    fn q(&mut self, a: usize, b: usize, k: usize, l: usize, r: usize) -> Option<T::R> {
        self.eval(k, l, r);
        if r <= a || b <= l {
            return None;
        }
        if a <= l && r <= b {
            Some(T::result(&self.buf[k]))
        } else {
            let vl = self.q(a, b, k * 2 + 1, l, (l + r) / 2);
            let vr = self.q(a, b, k * 2 + 2, (l + r) / 2, r);
            match (vl, vr) {
                (Some(l), Some(r)) => Some(T::reduce_result(l, r)),
                (Some(l), None) => Some(l),
                (None, Some(r)) => Some(r),
                _ => None,
            }
        }
    }
    #[allow(dead_code)]
    fn query(&mut self, a: usize, b: usize) -> Option<T::R> {
        let n = self.n;
        self.q(a, b, 0, 0, n)
    }
}
trait SEGimpl {
    type Elem: Clone;
    type A;
    type R;
    fn eval(parent: &mut Self::Elem, children: Option<(&mut Self::Elem, &mut Self::Elem)>);
    fn range(x: &Self::A, elem: &mut Self::Elem, l: usize, r: usize);
    fn reduce(parent: &mut Self::Elem, c1: &Self::Elem, c2: &Self::Elem);
    fn result(elem: &Self::Elem) -> Self::R;
    fn reduce_result(a: Self::R, b: Self::R) -> Self::R;
}

struct RangeOverwriteRMQ;

impl SEGimpl for RangeOverwriteRMQ {
    type Elem = (u64, Option<u64>);
    type A = u64;
    type R = u64;
    fn eval(parent: &mut Self::Elem, children: Option<(&mut Self::Elem, &mut Self::Elem)>) {
        if let Some(x) = parent.1.take() {
            parent.0 = x;
            if let Some((c1, c2)) = children {
                *c1 = (x, Some(x));
                *c2 = (x, Some(x));
            }
        }
    }
    #[allow(unused_variables)]
    fn range(x: &Self::A, elem: &mut Self::Elem, l: usize, r: usize) {
        elem.1 = Some(*x);
    }
    fn reduce(parent: &mut Self::Elem, c1: &Self::Elem, c2: &Self::Elem) {
        parent.0 = min(c1.0, c2.0);
    }
    fn result(elem: &Self::Elem) -> Self::R {
        elem.0
    }
    fn reduce_result(a: Self::R, b: Self::R) -> Self::R {
        min(a, b)
    }
}

fn main() {
    let (n, q) = get!(usize, usize);
    let mut seg: SEG<RangeOverwriteRMQ> = SEG::new(n, ((1 << 31) - 1, None));

    for _ in 0..q {
        let v = util::gets::<usize>();
        if v[0] == 0 {
            seg.range_add(&(v[3] as u64), v[1], v[2] + 1);
        } else {
            println!("{}", seg.query(v[1], v[2] + 1).unwrap());
        }
    }
}