#include <bits/stdc++.h>


#define BUFFSIZE (1 << 20 | 1)


#define fgetc(f) (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, BUFFSIZE, f), p1 == p2) ? EOF : *p1 ++)

struct freader {
	char buf[BUFFSIZE], *p1 = buf, *p2 = buf;
	FILE *f;

	freader(FILE *f_ = stdin): f(f_) {
		setvbuf(f, NULL, _IONBF, 0);
	}

	template<typename T>
	void read(T &x) {
		char c;
		for (c = fgetc(f); c != EOF && (c < '0' || '9' < c) && c != '-'; c = fgetc(f));
		if (c == '-') for (x = 0, c = fgetc(f); c != EOF && '0' <= c && c <= '9'; c = fgetc(f)) x = (x << 3) + (x << 1) - (c ^ '0');
		else for (x = 0; c != EOF && '0' <= c && c <= '9'; c = fgetc(f)) x = (x << 3) + (x << 1) + (c ^ '0');
	}

	template<typename T, typename ... Args>
	void read(T &x, Args &...args) {
		return read(x), read(args...);
	}
} fin;

#undef fgetc


#undef BUFFSIZE


#define INF 0xffffffff


using namespace std;


struct Segment {
	long long f00, f01, f10, f11;
} tree[400003];


struct Node {
	int x, val;
	bool tp;
	Node() = default;
	Node(int x_, int val_, bool tp_): x(x_), val(val_), tp(tp_) {}
} b[200003];


int T, n;
int a[100003];


inline void pushUp(int u) {
	tree[u].f00 = min(max(tree[u << 1].f00, tree[u << 1 | 1].f00), max(tree[u << 1].f01, tree[u << 1 | 1].f10));
	tree[u].f01 = min(max(tree[u << 1].f00, tree[u << 1 | 1].f01), max(tree[u << 1].f01, tree[u << 1 | 1].f11));
	tree[u].f10 = min(max(tree[u << 1].f10, tree[u << 1 | 1].f00), max(tree[u << 1].f11, tree[u << 1 | 1].f10));
	tree[u].f11 = min(max(tree[u << 1].f10, tree[u << 1 | 1].f01), max(tree[u << 1].f11, tree[u << 1 | 1].f11));
}

void buildTree(int u, int L, int R) {
	if (L == R) {
		tree[u].f00 = a[L];
		tree[u].f01 = (L == n ? INF : a[L] + a[L + 1]);
		tree[u].f10 = -INF;
		tree[u].f11 = INF;
		return;
	}
	const int mid = (L + R) >> 1;
	buildTree(u << 1, L, mid);
	buildTree(u << 1 | 1, mid + 1, R);
	pushUp(u);
}

void update0(int u, int L, int R, int x) {
	if (L == R) {
		tree[u].f00 = INF;
		return;
	}
	const int mid = (L + R) >> 1;
	if (x <= mid) update0(u << 1, L, mid, x);
	else update0(u << 1 | 1, mid + 1, R, x);
	pushUp(u);
}

void update1(int u, int L, int R, int x) {
	if (L == R) {
		tree[u].f01 = INF;
		return;
	}
	const int mid = (L + R) >> 1;
	if (x <= mid) update1(u << 1, L, mid, x);
	else update1(u << 1 | 1, mid + 1, R, x);
	pushUp(u);
}


int main() {
	fin.read(T);
	while (T --) {
		int m = 0;
		long long ans = 0x3f3f3f3f3f3f3f3f;
		fin.read(n);
		for (int i = 1; i <= n; ++ i) fin.read(a[i]);
		for (int i = 1; i <= n; ++ i) b[++ m] = Node(i, a[i], false);
		for (int i = 1; i < n; ++ i) b[++ m] = Node(i, a[i] + a[i + 1], true);
		sort(b + 1, b + m + 1, [](Node n1, Node n2) {return n1.val < n2.val;});
		buildTree(1, 1, n);
		for (int i = 1; i <= m; ++ i) {
			ans = min(ans, (long long)(tree[1].f00) - b[i].val);
			if (b[i].tp) update1(1, 1, n, b[i].x);
			else update0(1, 1, n, b[i].x);
		}
		printf("%lld\n", ans);
	}
	return 0;
}