Problem:
Score : 500 points

Problem Statement

For two sequences S and T of length N consisting of 0 and 1, let us define f(S, T) as follows:

Consider repeating the following operation on S so that S will be equal to T. f(S, T) is the minimum possible total cost of those operations.

Change S_i (from 0 to 1 or vice versa). The cost of this operation is D \times C_i, where D is the number of integers j such that S_j \neq T_j (1 \leq j \leq N) just before this change.

There are 2^N \times (2^N - 1) pairs (S, T) of different sequences of length N consisting of 0 and 1. Compute the sum of f(S, T) over all of those pairs, modulo (10^9+7).

Constraints

1 \leq N \leq 2 \times 10^5

1 \leq C_i \leq 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N
C_1 C_2 \cdots C_N

Output

Print the sum of f(S, T), modulo (10^9+7).

Sample Input 1

1
1000000000

Sample Output 1

999999993

There are two pairs (S, T) of different sequences of length 2 consisting of 0 and 1, as follows:

S = (0), T = (1): by changing S_1 to 1, we can have S = T at the cost of 1000000000, so f(S, T) = 1000000000.

S = (1), T = (0): by changing S_1 to 0, we can have S = T at the cost of 1000000000, so f(S, T) = 1000000000.

The sum of these is 2000000000, and we should print it modulo (10^9+7), that is, 999999993.

Sample Input 2

2
5 8

Sample Output 2

124

There are 12 pairs (S, T) of different sequences of length 3 consisting of 0 and 1, which include:

S = (0, 1), T = (1, 0)

In this case, if we first change S_1 to 1 then change S_2 to 0, the total cost is 5 \times 2 + 8 = 18. We cannot have S = T at a smaller cost, so f(S, T) = 18.

Sample Input 3

5
52 67 72 25 79

Sample Output 3

269312

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;
import java.util.NoSuchElementException;

public class Main {

	static PrintWriter out;
	static InputReader ir;

	static void solve() {
		int n = ir.nextInt();
		long[] c = ir.nextLongArray(n);
		Arrays.sort(c);
		long res = 0;
		for (int i = n - 1; i >= 0; i--) {
			long l = n - 1 - i;
			long r = n - l - 1;
			long t = 0;
			if (l > 0)
				t = add(t, mul(l, modpow(2, l - 1)));
			t = add(t, modpow(2, l));
			res = add(res, mul(c[i], mul(t, modpow(2, l + 2 * r + 1))));
		}
		out.println(res);
	}

	static long mod = (long) 1e9 + 7;

	static long add(long a, long b) {
		return (a + b) % mod;
	}

	static long sub(long a, long b) {
		long d = a - b;
		while (d < 0)
			d += mod;
		return d;
	}

	static long mul(long a, long b) {
		return a * b % mod;
	}

	static long div(long a, long b) {
		return a * mod_inverse(b) % mod;
	}

	public static long[] fact(int n) {
		long[] ret = new long[n + 1];
		ret[0] = 1 % mod;
		for (int i = 1; i <= n; i++) {
			ret[i] = mul(ret[i - 1], i);
		}
		return ret;
	}

	private static long[] factInv(int n) {
		long[] ret = new long[n + 1];
		ret[0] = 1;
		for (int i = 1; i <= n; i++) {
			ret[i] = div(ret[i - 1], i);
		}
		return ret;
	}

	public static long comb(int n, int m, long[] fact, long[] factInv) {
		long ret = fact[n];
		ret = mul(ret, factInv[m]);
		ret = mul(ret, factInv[n - m]);
		return ret;
	}

	public static long[][] stirling(int n) {
		long[][] ret = new long[n + 1][n + 1];
		ret[0][0] = 1;
		for (int i = 1; i <= n; i++)
			for (int j = 1; j <= i; j++)
				ret[i][j] = add(ret[i - 1][j - 1], mul(ret[i - 1][j], j));
		return ret;
	}

	public static long mod_inverse(long a) {
		long[] ret = extgcd(a, mod);
		return add(mod, ret[0] % mod);
	}

	private static long[] extgcd(long a, long b) {
		long[] ret = new long[3];
		ret[2] = _extgcd(a, b, ret);
		return ret;
	}

	private static long _extgcd(long a, long b, long[] x) {
		long g = a;
		x[0] = 1;
		x[1] = 0;
		if (b != 0) {
			g = _extgcd(b, a % b, x);
			long temp = x[0];
			x[0] = x[1];
			x[1] = temp;
			x[1] -= (a / b) * x[0];
		}
		return g;
	}

	static long modpow(long a, long n) {
		long res = 1;
		while (n > 0) {
			if ((n & 1) != 0)
				res = res * a % mod;
			a = a * a % mod;
			n >>= 1;
		}
		return res;
	}

	public static void main(String[] args) {
		ir = new InputReader(System.in);
		out = new PrintWriter(System.out);
		solve();
		out.flush();
	}

	static class InputReader {

		private InputStream in;
		private byte[] buffer = new byte[1024];
		private int curbuf;
		private int lenbuf;

		public InputReader(InputStream in) {
			this.in = in;
			this.curbuf = this.lenbuf = 0;
		}

		public boolean hasNextByte() {
			if (curbuf >= lenbuf) {
				curbuf = 0;
				try {
					lenbuf = in.read(buffer);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (lenbuf <= 0)
					return false;
			}
			return true;
		}

		private int readByte() {
			if (hasNextByte())
				return buffer[curbuf++];
			else
				return -1;
		}

		private boolean isSpaceChar(int c) {
			return !(c >= 33 && c <= 126);
		}

		private void skip() {
			while (hasNextByte() && isSpaceChar(buffer[curbuf]))
				curbuf++;
		}

		public boolean hasNext() {
			skip();
			return hasNextByte();
		}

		public String next() {
			if (!hasNext())
				throw new NoSuchElementException();
			StringBuilder sb = new StringBuilder();
			int b = readByte();
			while (!isSpaceChar(b)) {
				sb.appendCodePoint(b);
				b = readByte();
			}
			return sb.toString();
		}

		public int nextInt() {
			if (!hasNext())
				throw new NoSuchElementException();
			int c = readByte();
			while (isSpaceChar(c))
				c = readByte();
			boolean minus = false;
			if (c == '-') {
				minus = true;
				c = readByte();
			}
			int res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res = res * 10 + c - '0';
				c = readByte();
			} while (!isSpaceChar(c));
			return (minus) ? -res : res;
		}

		public long nextLong() {
			if (!hasNext())
				throw new NoSuchElementException();
			int c = readByte();
			while (isSpaceChar(c))
				c = readByte();
			boolean minus = false;
			if (c == '-') {
				minus = true;
				c = readByte();
			}
			long res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res = res * 10 + c - '0';
				c = readByte();
			} while (!isSpaceChar(c));
			return (minus) ? -res : res;
		}

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

		public int[] nextIntArray(int n) {
			int[] a = new int[n];
			for (int i = 0; i < n; i++)
				a[i] = nextInt();
			return a;
		}

		public long[] nextLongArray(int n) {
			long[] a = new long[n];
			for (int i = 0; i < n; i++)
				a[i] = nextLong();
			return a;
		}

		public char[][] nextCharMap(int n, int m) {
			char[][] map = new char[n][m];
			for (int i = 0; i < n; i++)
				map[i] = next().toCharArray();
			return map;
		}
	}

	static void tr(Object... o) {
		out.println(Arrays.deepToString(o));
		out.flush();
	}
}