Method tribonacci

1137-n-th-tribonacci-number.rs:16–25

(n: i32)

// 动态规划
impl Solution {
    pub fn tribonacci(n: i32) -> i32 {
        let mut ret = vec![0; 38];
        ret[0] = 0;
        ret[1] = 1;
        ret[2] = 1;
        for i in 3..38 {
            ret[i] = ret[i-1] + ret[i-2] + ret[i-3];
        }
        ret[n as usize]
    }
}

fn main() {