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)

use std::cmp::min;
use std::io;
use std::io::prelude::*;
use std::iter::repeat;

struct MinSegTree {
    n: usize,
    nodes: Vec<i32>,
    lazy_nodes: Vec<Option<i32>>,
}

impl MinSegTree {
    fn new(n: usize) -> MinSegTree {
        let n = 1 << f64::log2(n as f64).ceil() as usize;
        MinSegTree {
            n,
            nodes: repeat(std::i32::MAX).take(2 * n - 1).collect(),
            lazy_nodes: repeat(None).take(2 * n - 1).collect(),
        }
    }

    fn update(&mut self, s: usize, t: usize, x: i32, ni: usize, l: usize, r: usize) {
        self.eval(ni);
        if r <= s || t <= l {
            return;
        }
        if s <= l && r <= t {
            self.lazy_nodes[ni] = Some(x);
            self.eval(ni);
            return;
        }
        let m = (l + r) / 2;
        self.update(s, t, x, 2 * ni + 1, l, m);
        self.update(s, t, x, 2 * ni + 2, m, r);
        self.nodes[ni] = min(self.nodes[2 * ni + 1], self.nodes[2 * ni + 2]);
    }

    fn eval(&mut self, ni: usize) -> i32 {
        match self.lazy_nodes[ni].take() {
            Some(x) => {
                self.nodes[ni] = x;
                if ni < self.n - 1 {
                    self.lazy_nodes[2 * ni + 1] = Some(x);
                    self.lazy_nodes[2 * ni + 2] = Some(x);
                }
            }
            None => {}
        }
        self.nodes[ni]
    }

    fn find(&mut self, s: usize, t: usize, ni: usize, l: usize, r: usize) -> i32 {
        self.eval(ni);
        if s <= l && r <= t {
            self.nodes[ni]
        } else if r <= s || t <= l {
            std::i32::MAX
        } else {
            let m = (l + r) / 2;
            min(
                self.find(s, t, 2 * ni + 1, l, m),
                self.find(s, t, 2 * ni + 2, m, r),
            )
        }
    }
}

fn main() {
    let stdin = io::stdin();
    let mut lines = stdin.lock().lines();

    let line0 = lines.next().unwrap().unwrap();
    let n = line0.split_whitespace().next().unwrap().parse().unwrap();

    let mut mst = MinSegTree::new(n);

    for l in lines.map(Result::unwrap) {
        let mut words = l.split_whitespace();
        let com = words.next().unwrap().parse().unwrap();
        let s: usize = words.next().unwrap().parse().unwrap();
        let t: usize = words.next().unwrap().parse().unwrap();
        let n = mst.n;
        match com {
            0 => {
                let x = words.next().unwrap().parse().unwrap();
                mst.update(s, t + 1, x, 0, 0, n);
            }
            1 => println!("{}", mst.find(s, t + 1, 0, 0, n)),
            _ => (),
        }
    }
}