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Problem

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Solution

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1

Difficulty: EASY

Avg. time to solve

10 min

Success Rate

90%

Problem Statement

Suggest Edit

```
The first line of the input contains an integer ‘T’ denoting the number of test cases.
The only line of each test case contains a single positive integer ‘N’ denoting the number of doors and persons.
```

```
The only line of output of each test case should contain a binary string representing the final status of doors.
```

```
You do not need to print anything, it has already been taken care of. Just implement the given function.
```

```
Can you solve this in O(N) time and using constant extra space. The output string does not count as extra space.
```

```
1 <= T <= 100
1 <= N <= 10^4
Where ‘T’ is the number of test cases, ‘N’ is the number of doors and persons.
Time Limit: 1 sec
```

```
2
2
4
```

```
10
1001
```

```
Test case 1:
Initially, all the doors are closed -> 00
The first person has an ID 1 so it will change the status of doors 1(1 * 1) and 2(1 * 2) -> 11
The second person has an ID 2 so it will change the status of door 2 (2 * 1)-> 10
Test case 2:
Initially, all the doors are closed -> 0000
The first person has an ID 1 so it will change the status of door 1, 2, 3 and 4 -> 1111
The second person has an ID 2 so it will change the status of door 2 and 4 -> 1010
The third person has an ID 3 so it will change the status of door 3-> 1000
The fourth person has an ID 4 so it will change the status of door 4 -> 1001
```

```
2
6
8
```

```
100100
10010000
```

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