Leetcode 509 Fibonacci Number

The Fibonacci numbers, commonly denoted F(n) form a sequence, called the Fibonacci sequence, such that each number is the sum of the two preceding ones, starting from 0 and 1. That is,

F(0) = 0,   F(1) = 1
F(N) = F(N - 1) + F(N - 2), for N > 1.

Given N, calculate F(N).

直接计算

没什么难的, 直接计算吧, 这都不会的话重学编程语言

class Solution {
public:
    int fib(int N) {
        if(N == 0 || N == 1)
            return N;
        int f_Nminus2 = 0;
        int f_Nminus1 = 1;
        int ans = 0;
        for(int i = 1; i < N; ++i)
        {
            ans = f_Nminus2 + f_Nminus1;
            f_Nminus2 = f_Nminus1;
            f_Nminus1 = ans;
        }
        return ans;
    }
};