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: import static java.lang.Math.max;
  import static java.lang.Math.min;
  import static java.lang.Math.abs;
  import java.util.*;
  import java.io.*;
  import java.math.*;
  
  /**
   *
   * @Har_Har_Mahadev
   */
  
  /**
   * Main , Solution , Remove Public
   */
  public class C {
  
  	public static void process() throws IOException {
  
  		int n = sc.nextInt();
  		long arr[] = sc.readArrayLong(n);
  		long l = 0, r = Integer.MAX_VALUE;
  		long ans = l;
  		while(l<=r) {
  			long mid = (l+r)/2;
  			if(isValid(arr, mid)) {
  				ans = mid;
  				l = mid+1;
  			}
  			else r = mid-1;
  		}
  		System.out.println(ans);
  
  	}
  
  	private static boolean isValid(long[] arr, long mid) {
  		int n = arr.length;
  		long my[] = new long[arr.length];
  		for(int i =0; i<arr.length; i++)my[i] = arr[i];
  		for(int i = n-1; i>=2; i--) {
  			if(mid > my[i])return false;
  			long have = ((my[i]-mid)/3) * 3;
  			have = min(have, arr[i]);
  			my[i]-=have;
  			my[i-1]+=have/3;
  			my[i-2]+=(have/3)*2;
  		}
  		if(my[0] >= mid && my[1] >= mid)return true;
  		return false;
  	}
  
  	//=============================================================================
  	//--------------------------The End---------------------------------
  	//=============================================================================
  	private static long INF = 2000000000000000000L, M = 1000000007, MM = 998244353;
  	private static int N = 0;
  
  	private static void google(int tt) {
  		System.out.print("Case #" + (tt) + ": ");
  	}
  
  	static FastScanner sc;
  	static FastWriter out;
  
  	public static void main(String[] args) throws IOException {
  		boolean oj = true;
  		if (oj) {
  			sc = new FastScanner();
  			out = new FastWriter(System.out);
  		} else {
  			sc = new FastScanner("input.txt");
  			out = new FastWriter("output.txt");
  		}
  		long s = System.currentTimeMillis();
  		int t = 1;
  		t = sc.nextInt();
  		int TTT = 1;
  		while (t-- > 0) {
  			//			google(TTT++);
  			process();
  		}
  		out.flush();
  		//		tr(System.currentTimeMillis()-s+"ms");
  	}
  
  	private static boolean oj = System.getProperty("ONLINE_JUDGE") != null;
  
  	private static void tr(Object... o) {
  		if (!oj)
  			System.err.println(Arrays.deepToString(o));
  	}
  
  	static class Pair implements Comparable<Pair> {
  		int x, y;
  
  		Pair(int x, int y) {
  			this.x = x;
  			this.y = y;
  		}
  
  		@Override
  		public int compareTo(Pair o) {
  			return Integer.compare(this.x, o.x);
  		}
  
  		/*
  		 	@Override
  		    public boolean equals(Object o) {
  		        if (this == o) return true;
  		        if (!(o instanceof Pair)) return false;
  		        Pair key = (Pair) o;
  		        return x == key.x && y == key.y;
  		    }
  		 
  		    @Override
  		    public int hashCode() {
  		        int result = x;
  		        result = 31 * result + y;
  		        return result;
  		    }
  		*/
  	}
  
  	/////////////////////////////////////////////////////////////////////////////////////////////////////////
  
  	static int ceil(int x, int y) {
  		return (x % y == 0 ? x / y : (x / y + 1));
  	}
  
  	static long ceil(long x, long y) {
  		return (x % y == 0 ? x / y : (x / y + 1));
  	}
  
  	static long sqrt(long z) {
  		long sqz = (long) Math.sqrt(z);
  		while (sqz * 1L * sqz < z) {
  			sqz++;
  		}
  		while (sqz * 1L * sqz > z) {
  			sqz--;
  		}
  		return sqz;
  	}
  
  	static int log2(int N) {
  		int result = (int) (Math.log(N) / Math.log(2));
  		return result;
  	}
  
  	public static long gcd(long a, long b) {
  		if (a > b)
  			a = (a + b) - (b = a);
  		if (a == 0L)
  			return b;
  		return gcd(b % a, a);
  	}
  
  	public static long lcm(long a, long b) {
  		return (a * b) / gcd(a, b);
  	}
  
  	public static int lower_bound(int[] arr, int x) {
  		int low = 0, high = arr.length - 1, mid = -1;
  		int ans = -1;
  		while (low <= high) {
  			mid = (low + high) / 2;
  
  			if (arr[mid] > x) {
  				high = mid - 1;
  			} else {
  				ans = mid;
  				low = mid + 1;
  			}
  		}
  
  		return ans;
  	}
  
  	public static int upper_bound(int[] arr, int x) {
  		int low = 0, high = arr.length - 1, mid = -1;
  		int ans = arr.length;
  		while (low < high) {
  			mid = (low + high) / 2;
  
  			if (arr[mid] >= x) {
  				ans = mid;
  				high = mid - 1;
  			} else {
  				low = mid + 1;
  			}
  		}
  
  		return ans;
  	}
  
  	static void ruffleSort(int[] a) {
  		Random get = new Random();
  		for (int i = 0; i < a.length; i++) {
  			int r = get.nextInt(a.length);
  			int temp = a[i];
  			a[i] = a[r];
  			a[r] = temp;
  		}
  		Arrays.sort(a);
  	}
  
  	static void ruffleSort(long[] a) {
  		Random get = new Random();
  		for (int i = 0; i < a.length; i++) {
  			int r = get.nextInt(a.length);
  			long temp = a[i];
  			a[i] = a[r];
  			a[r] = temp;
  		}
  		Arrays.sort(a);
  	}
  
  	static void reverseArray(int[] a) {
  		int n = a.length;
  		int arr[] = new int[n];
  		for (int i = 0; i < n; i++)
  			arr[i] = a[n - i - 1];
  		for (int i = 0; i < n; i++)
  			a[i] = arr[i];
  	}
  
  	static void reverseArray(long[] a) {
  		int n = a.length;
  		long arr[] = new long[n];
  		for (int i = 0; i < n; i++)
  			arr[i] = a[n - i - 1];
  		for (int i = 0; i < n; i++)
  			a[i] = arr[i];
  	}
  
  	//custom multiset (replace with HashMap if needed)
  	public static void push(TreeMap<Integer, Integer> map, int k, int v) {
  		//map[k] += v;
  		if (!map.containsKey(k))
  			map.put(k, v);
  		else
  			map.put(k, map.get(k) + v);
  	}
  
  	public static void pull(TreeMap<Integer, Integer> map, int k, int v) {
  		//assumes map[k] >= v
  		//map[k] -= v
  		int lol = map.get(k);
  		if (lol == v)
  			map.remove(k);
  		else
  			map.put(k, lol - v);
  	}
  
  	// compress Big value to Time Limit
  	public static int[] compress(int[] arr) {
  		ArrayList<Integer> ls = new ArrayList<Integer>();
  		for (int x : arr)
  			ls.add(x);
  		Collections.sort(ls);
  		HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();
  		int boof = 1; //min value
  		for (int x : ls)
  			if (!map.containsKey(x))
  				map.put(x, boof++);
  		int[] brr = new int[arr.length];
  		for (int i = 0; i < arr.length; i++)
  			brr[i] = map.get(arr[i]);
  		return brr;
  	}
  
  	// Fast Writer 
  
  	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();
  		}
  	}
  
  	// Fast Inputs
  	static class FastScanner {
  		//I don't understand how this works lmao
  		private int BS = 1 << 16;
  		private char NC = (char) 0;
  		private byte[] buf = new byte[BS];
  		private int bId = 0, size = 0;
  		private char c = NC;
  		private double cnt = 1;
  		private BufferedInputStream in;
  
  		public FastScanner() {
  			in = new BufferedInputStream(System.in, BS);
  		}
  
  		public FastScanner(String s) {
  			try {
  				in = new BufferedInputStream(new FileInputStream(new File(s)), BS);
  			} catch (Exception e) {
  				in = new BufferedInputStream(System.in, BS);
  			}
  		}
  
  		private char getChar() {
  			while (bId == size) {
  				try {
  					size = in.read(buf);
  				} catch (Exception e) {
  					return NC;
  				}
  				if (size == -1)
  					return NC;
  				bId = 0;
  			}
  			return (char) buf[bId++];
  		}
  
  		public int nextInt() {
  			return (int) nextLong();
  		}
  
  		public int[] readArray(int N) {
  			int[] res = new int[N];
  			for (int i = 0; i < N; i++) {
  				res[i] = (int) nextLong();
  			}
  			return res;
  		}
  
  		public long[] readArrayLong(int N) {
  			long[] res = new long[N];
  			for (int i = 0; i < N; i++) {
  				res[i] = nextLong();
  			}
  			return res;
  		}
  
  		public int[][] readArrayMatrix(int N, int M, int Index) {
  			if (Index == 0) {
  				int[][] res = new int[N][M];
  				for (int i = 0; i < N; i++) {
  					for (int j = 0; j < M; j++)
  						res[i][j] = (int) nextLong();
  				}
  				return res;
  			}
  			int[][] res = new int[N][M];
  			for (int i = 1; i <= N; i++) {
  				for (int j = 1; j <= M; j++)
  					res[i][j] = (int) nextLong();
  			}
  			return res;
  
  		}
  
  		public long[][] readArrayMatrixLong(int N, int M, int Index) {
  			if (Index == 0) {
  				long[][] res = new long[N][M];
  				for (int i = 0; i < N; i++) {
  					for (int j = 0; j < M; j++)
  						res[i][j] = nextLong();
  				}
  				return res;
  			}
  			long[][] res = new long[N][M];
  			for (int i = 1; i <= N; i++) {
  				for (int j = 1; j <= M; j++)
  					res[i][j] = nextLong();
  			}
  			return res;
  
  		}
  
  		public long nextLong() {
  			cnt = 1;
  			boolean neg = false;
  			if (c == NC)
  				c = getChar();
  			for (; (c < '0' || c > '9'); c = getChar()) {
  				if (c == '-')
  					neg = true;
  			}
  			long res = 0;
  			for (; c >= '0' && c <= '9'; c = getChar()) {
  				res = (res << 3) + (res << 1) + c - '0';
  				cnt *= 10;
  			}
  			return neg ? -res : res;
  		}
  
  		public double nextDouble() {
  			double cur = nextLong();
  			return c != '.' ? cur : cur + nextLong() / cnt;
  		}
  
  		public double[] readArrayDouble(int N) {
  			double[] res = new double[N];
  			for (int i = 0; i < N; i++) {
  				res[i] = nextDouble();
  			}
  			return res;
  		}
  
  		public String next() {
  			StringBuilder res = new StringBuilder();
  			while (c <= 32)
  				c = getChar();
  			while (c > 32) {
  				res.append(c);
  				c = getChar();
  			}
  			return res.toString();
  		}
  
  		public String nextLine() {
  			StringBuilder res = new StringBuilder();
  			while (c <= 32)
  				c = getChar();
  			while (c != '\n') {
  				res.append(c);
  				c = getChar();
  			}
  			return res.toString();
  		}
  
  		public boolean hasNext() {
  			if (c > 32)
  				return true;
  			while (true) {
  				c = getChar();
  				if (c == NC)
  					return false;
  				else if (c > 32)
  					return true;
  			}
  		}
  	}
  
  }
  