[leetcode]Add Binary

Potential improvement, 用1个loop, out of bound 用expression赋值0, 还有不需要用Integer value of 直接减一减就好了

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

public class Solution { public String addBinary(String a, String b) { if (a == null || a.equals("")) return b; if (b == null || b.equals("")) return a; int i = a.length()-1; int j = b.length()-1; int carry = 0; String result = ""; while (i >= 0 && j >= 0){ int v1 = Integer.valueOf(a.charAt(i--)+""); int v2 = Integer.valueOf(b.charAt(j--)+""); int sum = (v1+v2+carry)%2; carry = (v1+v2+carry)/2; result = sum+result; } while (i>=0){ int v1 = Integer.valueOf(a.charAt(i--)+""); int sum = (v1+carry)%2; carry = (v1+carry)/2; result = sum+result; } while (j>=0){ int v2 = Integer.valueOf(b.charAt(j--)+""); int sum = (v2+carry)%2; carry = (v2+carry)/2; result = sum+result; } if (carry == 1){ result = "1"+result; } return result; } }