20190721-2.md

时间复杂度题解

function recursive(n) {
    if (n <= 0) {
        console.log('finish');
    } else {
        n-=2;
        recursive(n);
        recursive(n);
    }
}

function foo(n){
    var i = 1;
    while(i <= n){
        i = i * 2;
    }
}