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传统题

2000ms

256MiB

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Statement

You are given a sequence $[a_1,\ldots,a_n]$ where each element $a_i$ is either $0$ or $1$ . You can apply several (possibly zero) operations to the sequence. In each operation, you select two integers $1\le l\le r\le |a|$ (where $|a|$ is the current length of $a$ ) and replace $[a_l,\ldots,a_r]$ with a single element $x$ , where $x$ is the majority of $[a_l,\ldots,a_r]$ .

Here, the majority of a sequence consisting of $0$ and $1$ is defined as follows: suppose there are $c_0$ zeros and $c_1$ ones in the sequence, respectively.

If $c_0\ge c_1$ , the majority is $0$ .
If $c_0<c_1$ , the majority is $1$ .

For example, suppose $a=[1,0,0,0,1,1]$ . If we select $l=1,r=2$ , the resulting sequence will be $[0,0,0,1,1]$ . If we select $l=4,r=6$ , the resulting sequence will be $[1,0,0,1]$ .

Determine if you can make $a=[1]$ with a finite number of operations.

Format

Input

Each test contains multiple test cases. The first line contains the number of test cases $t$ ( $1 \le t \le 4\cdot 10^4$ ). Description of the test cases follows.

The first line of each testcase contains one integer $n$ ( $1\le n\le 2\cdot 10^5$ ).

The second line of each testcase contains a string consisting of $0$ and $1$ , describing the sequence $a$ .

It's guaranteed that the sum of $n$ over all testcases does not exceed $2\cdot 10^5$ .

Output

For each testcase, if it's possible to make $a=[1]$ , print Yes. Otherwise, print No.

Sample

No
Yes
No
Yes
No

ShanghaiTech ACM 炸鱼杯

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题目: 46
开始于: 2024-12-10 23:00
结束于: 2024-12-15 13:00
持续时间: 110 小时
主持人: _Arahc_
参赛人数: 112

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