s0118_pascals_triangle.rs

struct Solution;

//leetcode submit region begin(Prohibit modification and deletion)
impl Solution {
    pub fn generate(num_rows: i32) -> Vec<Vec<i32>> {
        let mut dp = Vec::with_capacity(num_rows as usize);
        dp.push(vec![1; 1]);
        if num_rows == 1 {
            return dp;
        }
        dp.push(vec![1; 2]);
        for i in 2..num_rows {
            let mut layer = vec![1; (i + 1) as usize];
            for j in 1..i {
                layer[j as usize] =
                    dp[(i - 1) as usize][(j - 1) as usize] + dp[(i - 1) as usize][j as usize];
            }
            dp.push(layer);
        }
        dp
    }
}
//leetcode submit region end(Prohibit modification and deletion)

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

    #[test]
    fn test() {
        let triangle_5 = vec![
            vec![1],
            vec![1, 1],
            vec![1, 2, 1],
            vec![1, 3, 3, 1],
            vec![1, 4, 6, 4, 1],
        ];
        assert_eq!(Solution::generate(5), triangle_5);
    }
}