Problem 1699. Find last zero for each column

Given a numeric array of arbitrary size, return the row index of the last zero for each column. If a column contains all nonzero values, return 0 for that column. Your output should be a row vector.

Example

a = [0 0 9 0;
     0 0 1 8;
     0 0 4 0;
     0 0 2 3;
     0 6 7 5];

z = [5 4 0 3]