c_cpp 509斐波纳契数

Posted 2021-05-14

class Soultion {
public:
    int fib(int N) {
      if(N < 2) return N;
      else
        return fib(N - 1) + fib(N - 2);
    }
}

//Runtime: 0 ms, faster than 100.00%

class Solution {
public:
    int fib(int N) {
        if(N < 2) return N;
        int a = 0,b = 1,c = 0;
        
        for(int i = 0;i < N;++i){
            a = b;
            b = c;
            c = a + b;
        }
        
        return c;
    }
};