网易前端编程题第一道

var input = parseInt(readline());
var x = 0;
var ret = [];
if (input === 1) {
    print('1')
} else if (input === 2) {
	print ('2')
}else if (input > 2) {
    while (input % 2 === 0) {
        // 偶数
        ret.unshift(2);
        input = (input - 2) / 2
    }
    while (input % 2 !== 0) {
        ret.unshift(1);
        input = (input -1) /2
    }
    var str = ret.join('');
    print (str)
    }