1072. Flip Columns For Maximum Number of Equal Rows

Given a `matrix` consisting of 0s and 1s, we may choose any number of columns in the matrix and flip every cell in that column.  Flipping a cell changes the value of that cell from 0 to 1 or from 1 to 0.

Return the maximum number of rows that have all values equal after some number of flips.

Example 1:

```Input: [[0,1],[1,1]]
Output: 1
Explanation: After flipping no values, 1 row has all values equal.
```

Example 2:

```Input: [[0,1],[1,0]]
Output: 2
Explanation: After flipping values in the first column, both rows have equal values.
```

Example 3:

```Input: [[0,0,0],[0,0,1],[1,1,0]]
Output: 2
Explanation: After flipping values in the first two columns, the last two rows have equal values.
```

Note:

1. `1 <= matrix.length <= 300`
2. `1 <= matrix[i].length <= 300`
3. All `matrix[i].length`'s are equal
4. `matrix[i][j]` is `0` or `1`

1072. Flip Columns For Maximum Number of Equal Rows
``````struct Solution;

impl Solution {
fn max_equal_rows_after_flips(matrix: Vec<Vec<i32>>) -> i32 {
let n = matrix.len();
let m = matrix[0].len();
let mut res = vec![1; n];
for i in 0..n {
for j in 0..i {
let count: usize = matrix[i]
.iter()
.zip(matrix[j].iter())
.map(|(x, y)| if x == y { 1 } else { 0 })
.sum();
if count == 0 || count == m {
res[i] += 1;
res[j] += 1;
}
}
}
*res.iter().max().unwrap() as i32
}
}

#[test]
fn test() {
let matrix = vec_vec_i32![[0, 1], [1, 1]];
let res = 1;
assert_eq!(Solution::max_equal_rows_after_flips(matrix), res);
let matrix = vec_vec_i32![[0, 1], [1, 0]];
let res = 2;
assert_eq!(Solution::max_equal_rows_after_flips(matrix), res);
let matrix = vec_vec_i32![[0, 0, 0], [0, 0, 1], [1, 1, 0]];
let res = 2;
assert_eq!(Solution::max_equal_rows_after_flips(matrix), res);
}
``````