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 JAVA (judge verdict: Wrong Answer)

import java.io.*;
import java.util.*;


public class Main {

	private static Scanner sc;
	private static Printer pr;

	private static void solve() {
		int n = sc.nextInt();
		int[] data = new int[n];
		Arrays.fill(data, (1 << 31) - 1);
		RMQ_RUQ_SqrtDecomposition ruq = new RMQ_RUQ_SqrtDecomposition(data);

		int q = sc.nextInt();
		for (int i = 0; i < q; i++) {
			int cmd = sc.nextInt();

			if (cmd == 0) {
				int s = sc.nextInt();
				int t = sc.nextInt();
				int x = sc.nextInt();

				ruq.update(s, t + 1, x);
			} else if (cmd == 1) {
				int s = sc.nextInt();
				int t = sc.nextInt();

				pr.println(ruq.find(s, t + 1));
				pr.flush();
			}
		}
	}

	private static class RMQ_RUQ_SqrtDecomposition {
		int[] data;
		// bakets??????????´???????????????´????????????????????§???????????°NULL
		int[] bakets;
		// bakets??????????°????
		int[] mb;
		int n; // data???????´???°
		int d; // 1??????bakets?????§??????
		int m; // bakets?????°

		// bakets[] ??????????????????????????´?????????
		// x>=0????????????-1??????
		final static int NULL = -1;
		final static int INF = Integer.MAX_VALUE;

		public RMQ_RUQ_SqrtDecomposition(int[] data) {
			this.n = data.length;
			this.data = data;
			this.d = (int)Math.sqrt(n);

			this.m = (n + d - 1) / d;
			bakets = new int[m];
			Arrays.fill(bakets, NULL);

			mb = new int[m];
			Arrays.fill(mb, INF);
			for (int i = 0; i < n; i++) {
				int bi = i / d;
				mb[bi] = Math.min(mb[bi], data[i]);
			}
		}

		// l,r:0-indexed
		// [l,r)?????????update
		void update(int l, int r, int x) {
			int bl = l / d;
			int br = Math.min(r / d, m - 1);
			for (int i = bl; i <= br; i++) {
				int tmpl = i * d;
				int tmpr = Math.min((i + 1) * d, n);
				if (tmpl >= l && tmpr <= r) {
					bakets[i] = x;
					mb[i] = x;
				} else {
					if (bakets[i] != NULL) {
						for (int j = tmpl; j < tmpr; j++) {
							data[j] = bakets[i];
						}
					}
					bakets[i] = NULL;

					tmpl = Math.max(tmpl, l);
					tmpr = Math.min(tmpr, r);
					for (int j = tmpl; j < tmpr; j++) {
						data[j] = x;
					}

					tmpl = i * d;
					tmpr = Math.min((i + 1) * d, n);
					mb[i] = INF;
					for (int j = tmpl; j < tmpr; j++) {
						mb[i] = Math.min(mb[i], data[j]);
					}
				}
			}
		}

		// l,r:0-indexed
		// [l,r)?????????update
		int find(int l, int r) {
			int bl = l / d;
			int br = Math.min(r / d, m - 1);
			int ret = INF;
			for (int i = bl; i <= br; i++) {
				int tmpl = i * d;
				int tmpr = Math.min((i + 1) * d, n);
				if (tmpl >= l && tmpr <= r) {
					ret = Math.min(ret, mb[i]);
				} else {
					if (bakets[i] != NULL) {
						ret = Math.min(ret, mb[i]);
					} else {
						tmpl = Math.max(tmpl, l);
						tmpr = Math.min(tmpr, r);
						for (int j = tmpl; j < tmpr; j++) {
							ret = Math.min(ret, data[j]);
						}
					}
				}
			}

			return ret;
		}
	}

	// ---------------------------------------------------
	public static void main(String[] args) {
		sc = new Scanner(System.in);
		pr = new Printer(System.out);

		solve();

		pr.close();
		sc.close();
	}

	@SuppressWarnings("unused")
	private static class Scanner {
		BufferedReader br;

		Scanner (InputStream in) {
			br = new BufferedReader(new InputStreamReader(in));
		}

		private boolean isPrintable(int ch) {
			return ch >= '!' && ch <= '~';
		}

		private boolean isCRLF(int ch) {
			return ch == '\n' || ch == '\r' || ch == -1;
		}

		private int nextPrintable() {
			try {
				int ch;
				while (!isPrintable(ch = br.read())) {
					if (ch == -1) {
						throw new NoSuchElementException();
					}
				}

				return ch;
			} catch (IOException e) {
				throw new NoSuchElementException();
			}
		}

		String next() {
			try {
				int ch = nextPrintable();
				StringBuilder sb = new StringBuilder();
				do {
					sb.appendCodePoint(ch);
				} while (isPrintable(ch = br.read()));

				return sb.toString();
			} catch (IOException e) {
				throw new NoSuchElementException();
			}
		}

		int nextInt() {
			try {
				// parseInt from Integer.parseInt()
				boolean negative = false;
				int res = 0;
				int limit = -Integer.MAX_VALUE;
				int radix = 10;

				int fc = nextPrintable();
				if (fc < '0') {
					if (fc == '-') {
						negative = true;
						limit = Integer.MIN_VALUE;
					} else if (fc != '+') {
						throw new NumberFormatException();
					}
					fc = br.read();
				}
				int multmin = limit / radix;

				int ch = fc;
				do {
					int digit = ch - '0';
					if (digit < 0 || digit >= radix) {
						throw new NumberFormatException();
					}
					if (res < multmin) {
						throw new NumberFormatException();
					}
					res *= radix;
					if (res < limit + digit) {
						throw new NumberFormatException();
					}
					res -= digit;

				} while (isPrintable(ch = br.read()));

				return negative ? res : -res;
			} catch (IOException e) {
				throw new NoSuchElementException();
			}
		}

		long nextLong() {
			try {
				// parseLong from Long.parseLong()
				boolean negative = false;
				long res = 0;
				long limit = -Long.MAX_VALUE;
				int radix = 10;

				int fc = nextPrintable();
				if (fc < '0') {
					if (fc == '-') {
						negative = true;
						limit = Long.MIN_VALUE;
					} else if (fc != '+') {
						throw new NumberFormatException();
					}
					fc = br.read();
				}
				long multmin = limit / radix;

				int ch = fc;
				do {
					int digit = ch - '0';
					if (digit < 0 || digit >= radix) {
						throw new NumberFormatException();
					}
					if (res < multmin) {
						throw new NumberFormatException();
					}
					res *= radix;
					if (res < limit + digit) {
						throw new NumberFormatException();
					}
					res -= digit;

				} while (isPrintable(ch = br.read()));

				return negative ? res : -res;
			} catch (IOException e) {
				throw new NoSuchElementException();
			}
		}

		float nextFloat() {
			return Float.parseFloat(next());
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		String nextLine() {
			try {
				int ch;
				while (isCRLF(ch = br.read())) {
					if (ch == -1) {
						throw new NoSuchElementException();
					}
				}
				StringBuilder sb = new StringBuilder();
				do {
					sb.appendCodePoint(ch);
				} while (!isCRLF(ch = br.read()));

				return sb.toString();
			} catch (IOException e) {
				throw new NoSuchElementException();
			}
		}

		void close() {
			try {
				br.close();
			} catch (IOException e) {
//				throw new NoSuchElementException();
			}
		}
	}

	private static class Printer extends PrintWriter {
		Printer(PrintStream out) {
			super(out);
		}
	}
}