算法 | 斐波那契数列

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

#include <iostream>

using namespace std;

int fib(int N) {
    if(N < 2) {
        return N;
    }
    if(N == 2) {
        return 1;
    }
    int a = 0, b = 1, result=0;
    for(int i=2; i<=N; ++i) {
        result = a + b;
        a = b;
        b = result;
    }
    return result;
}

int fibRecursion(int N) {
    if (N < 2) {
        return N;
    } else if (N == 2) {
        return 1;
    } else {
        return fibRecursion(N - 1) + fibRecursion(N-2);
    }
}

func Fib(N int) int {
    if N < 2 {
        return N
    }
    if N == 2 {
        return 1
    }
    var a = 0
    var b = 1
    for i := 2; i <= N; i++ {
        a, b = b, a+b
    }
    return b
}