Problem Description

The Fibonacci Numbers{0，1，1，2，3，5，8，13，21，34，55…} are defined by the recurrence：
F0=0，F1=1，Fn = Fn - 1 + Fn - 2，n >= 2
Write a program to calculate the Fibonacci Numbers.

Input

Each case contains a number n and you are expected to calculate Fn.(0 <= n <= 30) 。

Output

For each case, print a number Fn on a separate line,which means the nth Fibonacci Number.

Sample Input

1

Sample Output

1

原题链接

• Codeup_1795：问题 A: Fibonacci

解题思路

• 状态转移方程：dp[i] = dp[i - 1] + dp[i - 2]

代码实现（C++）

#include <iostream>using namespace std;#define maxn 31int n;
int dp[maxn];int getDp(int n) {if (n == 0 || n == 1)return dp[n];if (dp[n] == -1)dp[n] = getDp(n - 1) + getDp(n - 2);return dp[n];
}int main() {for (int i = 0; i < maxn; i++)dp[i] = -1;dp[0] = 0;dp[1] = 1;while (~scanf("%d", &n))printf("%d\n", getDp(n));return 0;
}