Day 12 - LeetCode 67. Add Binary

LeetCode 67. Add Binary

題目

Given two binary strings, return their sum (also a binary string).

For example,

a = "11"
b = "1"
Return "100".

翻譯

給兩個字元字串，回傳他們的總和(以字元字串回傳)。
範例：

a = '11'
b = '1'
return '100'

二進位相加

想法

從個位數開始相加, 跑while 用餘數, 留下0或1, 2的話要加上進位

詳細參閱

https://discuss.leetcode.com/topic/68382/javascript-solution-beats-96

---

Code

/**
* @param {string} a
* @param {string} b
* @return {string}
*/
var addBinary = function(a, b) {

var result = "";
var i = a.length - 1;
var j = b.length - 1;
var carry = 0;

while (i >= 0 || j >= 0 || carry > 0) {
    //從最後位數開始計算
    carry += i >= 0 ? parseInt(a[i--]) : 0;
    carry += j >= 0 ? parseInt(b[j--]) : 0;
    //用餘數方式看是0, 1
    result = carry % 2 + result;
    //carry=2 ,需要進位
    carry = parseInt(carry / 2);
}

return result;

};

Run

Your input
"0", "0"
"101010", "1110"

Your answer
"0"
"111000"

Expected answer
"0"
"111000"

Runtime: 138 ms