Fill array with 1's
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  Difficulty: Easy   Marks: 2

Given an array of 0 and 1. In how many iterations it is possible that the whole array can be filled with 1's, if in a single iteration immediate neighbours of 1's can be filled.

Input:
The first line contains a single integer T, the number of test cases. The first line consists of a single integer N(length of array). The next line consists of a N spaced integers(either 0 or 1).

Output:
For each testcase, print the minimum number of iterations to fill the whole array with 1's (if possible). If it is not possible to fill the array with 1s, print "-1" (without quotes).

Constraints:
1 <= T <= 103
1 <= N <= 107
0 <= Ai <= 1

Examples:
Input:
2
4
1 0 1 0
17
0 0 1 1 0 0 1 1 0 1 1 1 1 0 0 0 1

Output:
1
2

Explanation:
Test Case 1: Both the 0s has 1 as their immediate neighbour. So, we only need one iteration to fill the array with 1.

** For More Input/Output Examples Use 'Expected Output' option **

Contributor: Admin
Author: saksham0751


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