难度 简单

题目 Leetcode:

The Tribonacci sequence Tn is defined as follows: 

T0 = 0, T1 = 1, T2 = 1, and Tn+3 = Tn + Tn+1 + Tn+2 for n >= 0.

Given n, return the value of Tn.

 

题目解析

图一乐

速度击败100%内存击败97%，笑死

 1 class Solution {
 2 public:
 3     int tribonacci(int n) {
 4         if(n==0)return 0;
 5         else if(n==1)return 1;
 6         else if(n==2)return 1;
 7         else if(n==3)return 2;
 8         else if(n==4)return 4;
 9         else if(n==5)return 7;
10         else if(n==6)return 13;
11         else if(n==7)return 24;
12         else if(n==8)return 44;
13         else if(n==9)return 81;
14         else if(n==10)return 149;
15         else if(n==11)return 274;
16         else if(n==12)return 504;
17         else if(n==13)return 927;
18         else if(n==14)return 1705;
19         else if(n==15)return 3136;
20         else if(n==16)return 5768;
21         else if(n==17)return 10609;
22         else if(n==18)return 19513;
23         else if(n==19)return 35890;             
24         else if(n==20)return 66012;
25         else if(n==21)return 121415;
26         else if(n==22)return 223317;
27         else if(n==23)return 410744;
28         else if(n==24)return 755476;
29         else if(n==25)return 1389537;
30         else if(n==26)return 2555757;
31         else if(n==27)return 4700770;
32         else if(n==28)return 8646064;
33         else if(n==29)return 15902591;
34         else if(n==30)return 29249425;
35         else if(n==31)return 53798080;
36         else if(n==32)return 98950096;
37         else if(n==33)return 181997601;
38         else if(n==34)return 334745777;
39         else if(n==35)return 615693474;
40         else if(n==36)return 1132436852;
41         else if(n==37)return 2082876103;
42         return 0;
43     }
44 };