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 C++14 (judge verdict: Accepted)

#include "iostream"
#include "climits"
#include "list"
#include "queue"
#include "stack"
#include "set"
#include "functional"
#include "algorithm"
#include "string"
#include "map"
#include "unordered_map"
#include "unordered_set"
#include "iomanip"
#include "cmath"
#include "random"
#include "bitset"
#include "cstdio"
#include "numeric"

using namespace std;

const long long int MOD = 1000000007;

long long int N, M, K, H, W, L, R;

class Segment_Tree {
	vector<long long int>v;
	vector<long long int>add;
	vector<long long int>modi;
	vector<int>l;
	vector<int>r;
	int num;
	long long int ret;
	bool is_min;
	void Left(int place) {
		if (place >= v.size() / 2) {
			l[place] = place - v.size() / 2;
			return;
		}
		Left(place * 2);
		Left(place * 2 + 1);
		l[place] = l[place * 2];
		return;
	}
	void Right(int place) {
		if (place >= v.size() / 2) {
			r[place] = place - v.size() / 2;
			return;
		}
		Right(place * 2);
		Right(place * 2 + 1);
		r[place] = r[place * 2 + 1];
		return;
	}
	long long int Update(int place) {
		if (place >= v.size() / 2) {
			return v[place];
		}
		if (is_min) {
			v[place] = min(Update(place * 2), Update(place * 2 + 1));
			return v[place];
		}
		v[place] = max(Update(place * 2), Update(place * 2 + 1));
		return v[place];
	}
	void Modify(int a, int b, long long int num, int place) {
		if (l[place] >= a && r[place] <= b) {
			modi[place] = num;
			v[place] = num;
			add[place] = 0;
			return;
		}
		if (l[place] > b || r[place] < a)return;
		if (modi[place] != LLONG_MAX) {
			modi[place * 2] = modi[place * 2 + 1] = modi[place];
			v[place * 2] = v[place * 2 + 1] = modi[place];
			add[place * 2] = add[place * 2 + 1] = 0;
			modi[place] = LLONG_MAX;
		}
		Modify(a, b, num, place * 2);
		Modify(a, b, num, place * 2 + 1);
		if(is_min)v[place] = min(v[place * 2] + add[place * 2], v[place * 2 + 1] + add[place * 2 + 1]);
		else v[place] = max(v[place * 2] + add[place * 2], v[place * 2 + 1] + add[place * 2 + 1]);
		return;
	}
	void Add(int a, int b, long long int num, int place) {
		if (l[place] >= a && r[place] <= b) {
			if (modi[place] != LLONG_MAX) {
				if (place * 2 < v.size()) {
					modi[place * 2] = modi[place * 2 + 1] = modi[place];
					v[place * 2] = v[place * 2 + 1] = modi[place];
					add[place * 2] = add[place * 2 + 1] = 0;
				}
				modi[place] = LLONG_MAX;
			}
			add[place] += num;
			return;
		}
		if (l[place] > b || r[place] < a)return;
		if (modi[place] != LLONG_MAX) {
			modi[place * 2] = modi[place * 2 + 1] = modi[place];
			v[place * 2] = v[place * 2 + 1] = modi[place];
			add[place * 2] = add[place * 2 + 1] = 0;
			modi[place] = LLONG_MAX;
		}
		Add(a, b, num, place * 2);
		Add(a, b, num, place * 2 + 1);
		if (is_min)v[place] = min(v[place * 2] + add[place * 2], v[place * 2 + 1] + add[place * 2 + 1]);
		else v[place] = max(v[place * 2] + add[place * 2], v[place * 2 + 1] + add[place * 2 + 1]);
		return;
	}
	void RMQ(int a, int b, int place) {
		if (l[place] >= a && r[place] <= b) {
			if (modi[place] != LLONG_MAX) {
				if (place * 2 < v.size()) {
					modi[place * 2] = modi[place * 2 + 1] = modi[place];
					v[place * 2] = v[place * 2 + 1] = modi[place];
					add[place * 2] = add[place * 2 + 1] = 0;
				}
				modi[place] = LLONG_MAX;
			}
			if (is_min)ret = min(ret, v[place] + add[place]);
			else ret = max(ret, v[place] + add[place]);
			return;
		}
		if (l[place]>b || r[place]<a) return;
		if (modi[place] != LLONG_MAX) {
			modi[place * 2] = modi[place * 2 + 1] = modi[place];
			v[place * 2] = v[place * 2 + 1] = modi[place];
			add[place * 2] = add[place * 2 + 1] = 0;
			modi[place] = LLONG_MAX;
		}
		RMQ(a, b, place * 2);
		RMQ(a, b, place * 2 + 1);
		return;
	}
public:
	Segment_Tree(int n, bool min) {
		n++;
		num = 1;
		while (num < n * 2) {
			num *= 2;
		}
		l.resize(num);
		r.resize(num);
		is_min = min;
		if (min) {
			v.resize(num, LLONG_MAX);
		}
		else v.resize(num, LLONG_MIN);
		add.resize(num, 0);
		modi.resize(num, LLONG_MAX);
		Left(1);
		Right(1);
	}
	void Insert(int place, long long int num, bool update) {
		place += v.size() / 2;
		v[place] = num;
		if (!update)return;
		place /= 2;
		while (place) {
			if (is_min)v[place] = min(v[place * 2], v[place * 2 + 1]);
			else v[place] = max(v[place * 2], v[place * 2 + 1]);
			place /= 2;
		}
	}
	void Modify(int a, int b, long long int num) {
		Modify(a, b, num, 1);
	}
	void Add(int a, int b, long long int num) {
		Add(a, b, num, 1);
	}
	void Init() {
		Update(1);
	}
	long long int RMQ(int a, int b) {
		if (is_min)ret = LLONG_MAX;
		else ret = LLONG_MIN;
		RMQ(a, b, 1);
		return ret;
	}
};

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	cin >> N >> K;
	Segment_Tree sg(N, true);
	for (int i = 0; i < N; i++) {
		sg.Insert(i, (1LL << 31) - 1,false);
	}
	sg.Init();
	vector<int>ans;
	for (int i = 0; i < K; i++) {
		cin >> M;
		if (M) {
			cin >> L >> R;
			ans.push_back(sg.RMQ(L, R));
		}
		else {
			cin >> L >> R >> H;
			sg.Modify(L, R, H);
			//for (int j = 0; j < N; j++) {
			//	for (int k = j; k < N; k++) {
			//		cout << j << " " << k << " " << sg.RMQ(j, k) << endl;
			//	}
			//}
		}
	}
	for (auto i : ans)cout << i << endl;
	return 0;
}