6

Find K-th Row

Difficulty: EASY
Contributed By
Hardik Aggarwal
Avg. time to solve
15 min
Success Rate
80%

Problem Statement

Given a square binary matrix ‘mat[n][n]’, find ‘K’ such that all elements in the Kth row are ‘0’ and all elements in the Kth column are ‘1’. The value of mat[k][k] can be anything (either ‘0’ or ‘1’). If no such k exists, return ‘-1’.

For example
Consider the following matrix :
0 1 1 
0 1 0 
1 1 0 

You can see that row 1 (0-based) contains all 0’s except mat[1][1] and column 1 contains all 1’s. Hence the answer for the above case is 1.
Input format :
The first line contains a single integer ‘T’ denoting the number of test cases to be run. Then the test cases follow.

The first line of each test case contains an integer N representing the number in the problem statement.

Then N lines follow, each of which contains N space-separated integers denoting the elements of the matrix.
Output Format :
 For each test case print an integer denoting the value of K if such K exists else print -1.

 Output for each test case will be printed in a separate line.
Note:
You are not required to print anything; it has already been taken care of. Just implement the function.
Constraints:
1 <= T <= 5
1 <= N <= 1000
0 <= Aij <= 1
Time Limit: 1sec
Sample Input 1 :
1
3
0 1 1 
0 1 0 
1 1 0 
Sample Output 1 :
1
Explanation For Sample Output 1:
For the first test case, column 1 contains all ones. Also except mat[1][1] all numbers in row 1 are 0.
Sample Input 2:
2
2
0 1
1 0
2
0 0
1 0
Sample Output 2:
-1
0
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