66. Plus One

Given a non-negative number represented as an array of digits, plus one to the number.

The digits are stored such that the most significant digit is at the head of the list.
这个就是想让你自己实现十进制加一咯，用一个进位来统一管理，各位加的一就假装是进上来的。

/**
 * @param {number[]} digits
 * @return {number[]}
 */
var plusOne = function(digits) {
    var num = digits.length;
    var jinwei = 1;
    for (var i = num-1; i>=0; i--) {
        digits[i] = digits[i]+jinwei;
        if (digits[i]<10) {
            break;
        } else {
            jinwei = 1;
            digits[i] -= 10;
            if (i===0) {
                digits.unshift(1);
            }
        }
    }
    return digits;
};