n0059_spiral_matrix_ii.rs

/**
 * [59] Spiral Matrix II
 *
 * Given a positive integer n, generate a square matrix filled with elements from 1 to n^2 in spiral order.
 * 
 * Example:
 * 
 * 
 * Input: 3
 * Output:
 * [
 *  [ 1, 2, 3 ],
 *  [ 8, 9, 4 ],
 *  [ 7, 6, 5 ]
 * ]
 * 
 * 
 */
pub struct Solution {}

// submission codes start here

impl Solution {
    pub fn generate_matrix(n: i32) -> Vec<Vec<i32>> {
        let mut res = vec![vec![0; n as usize]; n as usize];
        if n < 1 { return res }
        let (mut x_min, mut x_max, mut y_min, mut y_max) = (0, n as usize, 0, n as usize);
        let mut i = 1;
        loop {
            for y in y_min..y_max { res[x_min][y] = i; i+=1; }
            x_min += 1;
            if x_min == x_max { break }
            for x in x_min..x_max { res[x][y_max-1] = i; i+=1; }
            y_max -= 1;
            if y_min == y_max { break }
            for y in (y_min..y_max).rev() { res[x_max-1][y] = i; i+=1; }
            x_max -= 1;
            if x_min == x_max { break }
            for x in (x_min..x_max).rev() { res[x][y_min] = i; i+=1; }
            y_min += 1;
            if y_min == y_max { break }
        }
        res
    }
}

// submission codes end

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

    #[test]
    fn test_59() {
        assert_eq!(Solution::generate_matrix(1), vec![vec![1]]);
        assert_eq!(Solution::generate_matrix(2), vec![vec![1,2],vec![4,3]]);
        assert_eq!(
            Solution::generate_matrix(3),
            vec![
                vec![1,2,3],
                vec![8,9,4],
                vec![7,6,5],
            ]);
    }
}