#### Maximal Square

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```use std::cmp::max;
use std::cmp::min;

/// Maximal Square
///
/// Given an `m` * `n` binary matrix filled with 0's and 1's, find the largest square containing only 1's and return its area.\
/// <https://leetcode.com/problems/maximal-square/>
///
/// # Arguments:
///   * `matrix` - an array of integer array
///
/// # Complexity
///   - time complexity: O(n^2),
///   - space complexity: O(n),
pub fn maximal_square(matrix: &mut [Vec<i32>]) -> i32 {
if matrix.is_empty() {
return 0;
}

let rows = matrix.len();
let cols = matrix[0].len();
let mut result: i32 = 0;

for row in 0..rows {
for col in 0..cols {
if matrix[row][col] == 1 {
if row == 0 || col == 0 {
result = max(result, 1);
} else {
let temp = min(matrix[row - 1][col - 1], matrix[row - 1][col]);

let count: i32 = min(temp, matrix[row][col - 1]) + 1;
result = max(result, count);

matrix[row][col] = count;
}
}
}
}

result * result
}

#[cfg(test)]
mod tests {
use super::*;

#[test]
fn test() {
assert_eq!(maximal_square(&mut []), 0);

let mut matrix = vec![vec![0, 1], vec![1, 0]];
assert_eq!(maximal_square(&mut matrix), 1);

let mut matrix = vec![
vec![1, 0, 1, 0, 0],
vec![1, 0, 1, 1, 1],
vec![1, 1, 1, 1, 1],
vec![1, 0, 0, 1, 0],
];
assert_eq!(maximal_square(&mut matrix), 4);

let mut matrix = vec![vec![0]];
assert_eq!(maximal_square(&mut matrix), 0);
}
}
```