https://leetcode.com/problems/minimum-falling-path-sum/

minimum_falling_path_sum.rs

impl Solution {
    pub fn min_falling_path_sum(a: Vec<Vec<i32>>) -> i32 {
        let mut prev: Vec<i32> = a[0].clone();
        let mut curr: Vec<i32> = vec![0; a[0].len()];
        for i in 1..a.len() {
            for j in 0..a[i].len() {
                let mut sum_so_far = prev[j];
                if j > 0 {
                    sum_so_far = std::cmp::min(sum_so_far, prev[j-1]);
                }
                if j < a[i].len() - 1 {
                    sum_so_far = std::cmp::min(sum_so_far, prev[j+1]);
                }
                curr[j] = a[i][j] + sum_so_far;
            }
            std::mem::swap(&mut curr, &mut prev);
        }
        *prev.iter().min().unwrap()
    }
}