[leetcode]67.Add Binary
阿新 • • 發佈:2018-10-01
ngs turn 結果 一個 += return 兩個 har ddb
題目
Given two binary strings, return their sum (also a binary string).
The input strings are both non-empty and contains only characters 1 or 0.
Example 1:
Input: a = "11", b = "1"
Output: "100"
Example 2:
Input: a = "1010", b = "1011"
Output: "10101"
解法
思路
用兩個指針分別指向a和b的末尾,將a和b最後一位分別轉為數字,用carry來保存要進位的數字,初始為0。如果a和b相加結束後,carry為1,則在sb之後加一個1,最後將sb逆轉就可得到最終的結果,當然,這裏也是可以用棧來代替reverse()的。
代碼
class Solution { public String addBinary(String a, String b) { StringBuilder sb = new StringBuilder(); int i = a.length() - 1; int j = b.length() - 1; int carry = 0; while(i >= 0 || j >= 0) { int sum = carry; if(i >= 0) sum += a.charAt(i--) - ‘0‘; if(j >= 0) sum += b.charAt(j--) - ‘0‘; sb.append(sum % 2); carry = sum / 2; } if(carry == 1) sb.append(carry); return sb.reverse().toString(); } }
[leetcode]67.Add Binary