1390 小矩形覆盖

1，递归方法超时

2，int型存储溢出

3，Output Limit Exceeded错误

4，数学归纳法处理问题

#include<iostream>#include<cstdio>using namespace std;unsigned long a[71];int fun(int n){for(int i=1;i<=n;i++)if(i == 1)a[i] = 1;else if(i ==2)a[i] = 2;elsea[i] = a[i-1] + a[i-2];return a[n];}int main(){int input;while(scanf("%d",&input)!=EOF){printf("%lu\n",fun(input));}return 1;}