JS斐波那契数列O(n)

function fibonacci(n) {
    return fib(n)[n]
}
var fib=(function(n){
    var meo=[0,1]
    return function(n){
        for(var i=meo.length;i<=n;i++){
            meo[i]=meo[i-1]+meo[i-2]
        }
        return meo.slice(0,n+1)
    }
})()

以上空间复杂度：o(n)，时间复杂度：o(n)，最快 o(1)

 

 

2.运用大数加法：

var _fib = (function (n) {
    var memory = ['0', '1'];

    function add(a, b) {
        var res = '',
            c = 0;
        a = a.split('');
        b = b.split('');
        while (a.length || b.length || c) {
            c += ~~a.pop() + ~~b.pop();
            res = c % 10 + res;
            c = c > 9;
        }
        return res.replace(/^0+/, '');
    }

    return function (n) {
        for (var i = memory.length; i <= n; i++) {
            memory[i] = add(memory[i - 1], memory[i - 2]);
        }
        //console.log(memory.length + ' numbers saved.');
        return memory.slice(0, n + 1);
    };
})();

var fibonacci = function (n) {
    return _fib(n)[n];
}