description: There are n heaps of stone. The i-th heap has h_i stones. You want to change the number of stones in the heap by performing the following process once: 
  
    * You go through the heaps from the 3-rd heap to the n-th heap, in this order. 
    * Let i be the number of the current heap. 
    * You can choose a number d (0 ≤ 3 ⋅ d ≤ h_i), move d stones from the i-th heap to the (i - 1)-th heap, and 2 ⋅ d stones from the i-th heap to the (i - 2)-th heap. 
    * So after that h_i is decreased by 3 ⋅ d, h_{i - 1} is increased by d, and h_{i - 2} is increased by 2 ⋅ d. 
    * You can choose different or same d for different operations. Some heaps may become empty, but they still count as heaps. 
  
  
  
  What is the maximum number of stones in the smallest heap after the process?
  
  Input
  
  Each test contains multiple test cases. The first line contains the number of test cases t (1 ≤ t ≤ 2⋅ 10^5). Description of the test cases follows.
  
  The first line of each test case contains a single integer n (3 ≤ n ≤ 2 ⋅ 10^5).
  
  The second lines of each test case contains n integers h_1, h_2, h_3, …, h_n (1 ≤ h_i ≤ 10^9).
  
  It is guaranteed that the sum of n over all test cases does not exceed 2 ⋅ 10^5.
  
  Output
  
  For each test case, print the maximum number of stones that the smallest heap can contain.
  
  Example
  
  Input
  
  
  4
  4
  1 2 10 100
  4
  100 100 100 1
  5
  5 1 1 1 8
  6
  1 2 3 4 5 6
  
  
  Output
  
  
  7
  1
  1
  3
  
  Note
  
  In the first test case, the initial heap sizes are [1, 2, 10, 100]. We can move the stones as follows. 
  
    * move 3 stones and 6 from the 3-rd heap to the 2-nd and 1 heap respectively. The heap sizes will be [7, 5, 1, 100]; 
    * move 6 stones and 12 stones from the last heap to the 3-rd and 2-nd heap respectively. The heap sizes will be [7, 17, 7, 82]. 
  
  
  
  In the second test case, the last heap is 1, and we can not increase its size.
  
  In the third test case, it is better not to move any stones.
  
  In the last test case, the final achievable configuration of the heaps can be [3, 5, 3, 4, 3, 3].
solution: //package round763;
  import java.io.*;
  import java.util.ArrayDeque;
  import java.util.Arrays;
  import java.util.InputMismatchException;
  import java.util.Queue;
  
  public class C {
  	InputStream is;
  	FastWriter out;
  	String INPUT = "";
  	
  	void solve()
  	{
  		for(int T = ni();T > 0;T--)go();
  	}
  
  	void go()
  	{
  		int n = ni();
  		long[] a = nal(n);
  		long low = 0, high = 1000000007;
  		while(high - low > 1){
  			long h = high+low>>1;
  			if(ok(h, a)){
  				low = h;
  			}else{
  				high = h;
  			}
  		}
  		out.println(low);
  	}
  
  	boolean ok(long h, long[] a)
  	{
  		int n = a.length;
  		long[] buf = new long[n];
  		for(int i = n-1;i >= 0;i--){
  			if(a[i] + buf[i] < h)return false;
  			if(i >= 2) {
  				// a[i] + buf[i] >= h
  				//
  				long d = (a[i] - Math.max(h-buf[i], 0)) / 3;
  				buf[i - 2] += 2 * d;
  				buf[i - 1] += d;
  			}
  		}
  		return true;
  	}
  	
  	void run() throws Exception
  	{
  		is = oj ? System.in : new ByteArrayInputStream(INPUT.getBytes());
  		out = new FastWriter(System.out);
  		
  		long s = System.currentTimeMillis();
  		solve();
  		out.flush();
  		tr(System.currentTimeMillis()-s+"ms");
  	}
  	
  	public static void main(String[] args) throws Exception { new C().run(); }
  	
  	private byte[] inbuf = new byte[1024];
  	public int lenbuf = 0, ptrbuf = 0;
  	
  	private int readByte()
  	{
  		if(lenbuf == -1)throw new InputMismatchException();
  		if(ptrbuf >= lenbuf){
  			ptrbuf = 0;
  			try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
  			if(lenbuf <= 0)return -1;
  		}
  		return inbuf[ptrbuf++];
  	}
  	
  	private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
  	private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
  	
  	private double nd() { return Double.parseDouble(ns()); }
  	private char nc() { return (char)skip(); }
  	
  	private String ns()
  	{
  		int b = skip();
  		StringBuilder sb = new StringBuilder();
  		while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
  			sb.appendCodePoint(b);
  			b = readByte();
  		}
  		return sb.toString();
  	}
  	
  	private char[] ns(int n)
  	{
  		char[] buf = new char[n];
  		int b = skip(), p = 0;
  		while(p < n && !(isSpaceChar(b))){
  			buf[p++] = (char)b;
  			b = readByte();
  		}
  		return n == p ? buf : Arrays.copyOf(buf, p);
  	}
  
  	private int[] na(int n)
  	{
  		int[] a = new int[n];
  		for(int i = 0;i < n;i++)a[i] = ni();
  		return a;
  	}
  
  	private long[] nal(int n)
  	{
  		long[] a = new long[n];
  		for(int i = 0;i < n;i++)a[i] = nl();
  		return a;
  	}
  
  	private char[][] nm(int n, int m) {
  		char[][] map = new char[n][];
  		for(int i = 0;i < n;i++)map[i] = ns(m);
  		return map;
  	}
  
  	private int[][] nmi(int n, int m) {
  		int[][] map = new int[n][];
  		for(int i = 0;i < n;i++)map[i] = na(m);
  		return map;
  	}
  
  	private int ni() { return (int)nl(); }
  
  	private long nl()
  	{
  		long num = 0;
  		int b;
  		boolean minus = false;
  		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
  		if(b == '-'){
  			minus = true;
  			b = readByte();
  		}
  
  		while(true){
  			if(b >= '0' && b <= '9'){
  				num = num * 10 + (b - '0');
  			}else{
  				return minus ? -num : num;
  			}
  			b = readByte();
  		}
  	}
  
  	public static class FastWriter
  	{
  		private static final int BUF_SIZE = 1<<13;
  		private final byte[] buf = new byte[BUF_SIZE];
  		private final OutputStream out;
  		private int ptr = 0;
  
  		private FastWriter(){out = null;}
  
  		public FastWriter(OutputStream os)
  		{
  			this.out = os;
  		}
  
  		public FastWriter(String path)
  		{
  			try {
  				this.out = new FileOutputStream(path);
  			} catch (FileNotFoundException e) {
  				throw new RuntimeException("FastWriter");
  			}
  		}
  
  		public FastWriter write(byte b)
  		{
  			buf[ptr++] = b;
  			if(ptr == BUF_SIZE)innerflush();
  			return this;
  		}
  
  		public FastWriter write(char c)
  		{
  			return write((byte)c);
  		}
  
  		public FastWriter write(char[] s)
  		{
  			for(char c : s){
  				buf[ptr++] = (byte)c;
  				if(ptr == BUF_SIZE)innerflush();
  			}
  			return this;
  		}
  
  		public FastWriter write(String s)
  		{
  			s.chars().forEach(c -> {
  				buf[ptr++] = (byte)c;
  				if(ptr == BUF_SIZE)innerflush();
  			});
  			return this;
  		}
  
  		private static int countDigits(int l) {
  			if (l >= 1000000000) return 10;
  			if (l >= 100000000) return 9;
  			if (l >= 10000000) return 8;
  			if (l >= 1000000) return 7;
  			if (l >= 100000) return 6;
  			if (l >= 10000) return 5;
  			if (l >= 1000) return 4;
  			if (l >= 100) return 3;
  			if (l >= 10) return 2;
  			return 1;
  		}
  
  		public FastWriter write(int x)
  		{
  			if(x == Integer.MIN_VALUE){
  				return write((long)x);
  			}
  			if(ptr + 12 >= BUF_SIZE)innerflush();
  			if(x < 0){
  				write((byte)'-');
  				x = -x;
  			}
  			int d = countDigits(x);
  			for(int i = ptr + d - 1;i >= ptr;i--){
  				buf[i] = (byte)('0'+x%10);
  				x /= 10;
  			}
  			ptr += d;
  			return this;
  		}
  
  		private static int countDigits(long l) {
  			if (l >= 1000000000000000000L) return 19;
  			if (l >= 100000000000000000L) return 18;
  			if (l >= 10000000000000000L) return 17;
  			if (l >= 1000000000000000L) return 16;
  			if (l >= 100000000000000L) return 15;
  			if (l >= 10000000000000L) return 14;
  			if (l >= 1000000000000L) return 13;
  			if (l >= 100000000000L) return 12;
  			if (l >= 10000000000L) return 11;
  			if (l >= 1000000000L) return 10;
  			if (l >= 100000000L) return 9;
  			if (l >= 10000000L) return 8;
  			if (l >= 1000000L) return 7;
  			if (l >= 100000L) return 6;
  			if (l >= 10000L) return 5;
  			if (l >= 1000L) return 4;
  			if (l >= 100L) return 3;
  			if (l >= 10L) return 2;
  			return 1;
  		}
  
  		public FastWriter write(long x)
  		{
  			if(x == Long.MIN_VALUE){
  				return write("" + x);
  			}
  			if(ptr + 21 >= BUF_SIZE)innerflush();
  			if(x < 0){
  				write((byte)'-');
  				x = -x;
  			}
  			int d = countDigits(x);
  			for(int i = ptr + d - 1;i >= ptr;i--){
  				buf[i] = (byte)('0'+x%10);
  				x /= 10;
  			}
  			ptr += d;
  			return this;
  		}
  
  		public FastWriter write(double x, int precision)
  		{
  			if(x < 0){
  				write('-');
  				x = -x;
  			}
  			x += Math.pow(10, -precision)/2;
  			//		if(x < 0){ x = 0; }
  			write((long)x).write(".");
  			x -= (long)x;
  			for(int i = 0;i < precision;i++){
  				x *= 10;
  				write((char)('0'+(int)x));
  				x -= (int)x;
  			}
  			return this;
  		}
  
  		public FastWriter writeln(char c){
  			return write(c).writeln();
  		}
  
  		public FastWriter writeln(int x){
  			return write(x).writeln();
  		}
  
  		public FastWriter writeln(long x){
  			return write(x).writeln();
  		}
  
  		public FastWriter writeln(double x, int precision){
  			return write(x, precision).writeln();
  		}
  
  		public FastWriter write(int... xs)
  		{
  			boolean first = true;
  			for(int x : xs) {
  				if (!first) write(' ');
  				first = false;
  				write(x);
  			}
  			return this;
  		}
  
  		public FastWriter write(long... xs)
  		{
  			boolean first = true;
  			for(long x : xs) {
  				if (!first) write(' ');
  				first = false;
  				write(x);
  			}
  			return this;
  		}
  
  		public FastWriter writeln()
  		{
  			return write((byte)'\n');
  		}
  
  		public FastWriter writeln(int... xs)
  		{
  			return write(xs).writeln();
  		}
  
  		public FastWriter writeln(long... xs)
  		{
  			return write(xs).writeln();
  		}
  
  		public FastWriter writeln(char[] line)
  		{
  			return write(line).writeln();
  		}
  
  		public FastWriter writeln(char[]... map)
  		{
  			for(char[] line : map)write(line).writeln();
  			return this;
  		}
  
  		public FastWriter writeln(String s)
  		{
  			return write(s).writeln();
  		}
  
  		private void innerflush()
  		{
  			try {
  				out.write(buf, 0, ptr);
  				ptr = 0;
  			} catch (IOException e) {
  				throw new RuntimeException("innerflush");
  			}
  		}
  
  		public void flush()
  		{
  			innerflush();
  			try {
  				out.flush();
  			} catch (IOException e) {
  				throw new RuntimeException("flush");
  			}
  		}
  
  		public FastWriter print(byte b) { return write(b); }
  		public FastWriter print(char c) { return write(c); }
  		public FastWriter print(char[] s) { return write(s); }
  		public FastWriter print(String s) { return write(s); }
  		public FastWriter print(int x) { return write(x); }
  		public FastWriter print(long x) { return write(x); }
  		public FastWriter print(double x, int precision) { return write(x, precision); }
  		public FastWriter println(char c){ return writeln(c); }
  		public FastWriter println(int x){ return writeln(x); }
  		public FastWriter println(long x){ return writeln(x); }
  		public FastWriter println(double x, int precision){ return writeln(x, precision); }
  		public FastWriter print(int... xs) { return write(xs); }
  		public FastWriter print(long... xs) { return write(xs); }
  		public FastWriter println(int... xs) { return writeln(xs); }
  		public FastWriter println(long... xs) { return writeln(xs); }
  		public FastWriter println(char[] line) { return writeln(line); }
  		public FastWriter println(char[]... map) { return writeln(map); }
  		public FastWriter println(String s) { return writeln(s); }
  		public FastWriter println() { return writeln(); }
  	}
  
  	public void trnz(int... o)
  	{
  		for(int i = 0;i < o.length;i++)if(o[i] != 0)System.out.print(i+":"+o[i]+" ");
  		System.out.println();
  	}
  
  	// print ids which are 1
  	public void trt(long... o)
  	{
  		Queue<Integer> stands = new ArrayDeque<>();
  		for(int i = 0;i < o.length;i++){
  			for(long x = o[i];x != 0;x &= x-1)stands.add(i<<6|Long.numberOfTrailingZeros(x));
  		}
  		System.out.println(stands);
  	}
  
  	public void tf(boolean... r)
  	{
  		for(boolean x : r)System.out.print(x?'#':'.');
  		System.out.println();
  	}
  
  	public void tf(boolean[]... b)
  	{
  		for(boolean[] r : b) {
  			for(boolean x : r)System.out.print(x?'#':'.');
  			System.out.println();
  		}
  		System.out.println();
  	}
  
  	public void tf(long[]... b)
  	{
  		if(INPUT.length() != 0) {
  			for (long[] r : b) {
  				for (long x : r) {
  					for (int i = 0; i < 64; i++) {
  						System.out.print(x << ~i < 0 ? '#' : '.');
  					}
  				}
  				System.out.println();
  			}
  			System.out.println();
  		}
  	}
  
  	public void tf(long... b)
  	{
  		if(INPUT.length() != 0) {
  			for (long x : b) {
  				for (int i = 0; i < 64; i++) {
  					System.out.print(x << ~i < 0 ? '#' : '.');
  				}
  			}
  			System.out.println();
  		}
  	}
  
  	private boolean oj = System.getProperty("ONLINE_JUDGE") != null;
  	private void tr(Object... o) { if(!oj)System.out.println(Arrays.deepToString(o)); }
  }
  