GuilinDev

Lc1137

05 August 2008

1137. N-th Tribonacci Number

斐波那契数三个数的情况

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class Solution {
    Map<Integer, Integer> map = new HashMap<>();
    public int tribonacci(int n) {
        if (n < 2) {
            return n;
        }
        if (n == 2) {
            return 1;
        }
        if (!map.containsKey(n)) {
            map.put(n, tribonacci(n - 1) + tribonacci(n - 2) + tribonacci(n - 3));
        }
        return map.get(n);
    }
}