题目：
Time
Limit: 2000/1000 MS (Java/Others) Memory Limit:
65536/32768 K (Java/Others)
Total Submission(s):
27908 Accepted Submission(s):
11145
1 #include<stdio.h> 2 int main(){ 3 int m; 4 double ans[51]; 5 ans[1] = 3; 6 ans[2] = 6; 7 ans[3] = 6; 8 for(int i=4;i<51;i++){ 9 ans[i] = ans[i-1] + 2*ans[i-2]; 10 } 11 while(scanf("%d", &m)!=EOF){ 12 printf("%.0lf\n", ans[m]); 13 } 14 }
原文：http://www.cnblogs.com/epodongfeng/p/3679601.html