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"
1 class Solution { 2 public: 3 string addBinary(string a, string b) { 4 int la = a.length(); 5 int lb = b.length(); 6 string res = ""; 7 int car = 0; 8 if(la <= lb) { 9 for(int i = la - 1; i >= 0; i--) { 10 if(a[i] == '1' && b[lb - (la - i)] == '1') { 11 if(car == 1) 12 res = '1' + res; 13 else { 14 res = '0' + res; 15 car = 1; 16 } 17 } 18 else if(a[i] != b[lb - (la - i)]) { 19 if(car == 1) 20 res = '0' + res; 21 else 22 res = '1' + res; 23 } 24 else { 25 if(car == 1) { 26 res = '1' + res; 27 car = 0; 28 } 29 else 30 res = '0' + res; 31 } 32 } 33 for(int i = lb - la - 1; i >= 0; i--) { 34 if(b[i] == '1') { 35 if(car == 1) 36 res = '0' + res; 37 else 38 res = '1' + res; 39 } 40 else { 41 if(car == 1) { 42 res = '1' + res; 43 car = 0; 44 } 45 else 46 res = '0' + res; 47 } 48 } 49 if(car == 1) { 50 res = '1' + res; 51 } 52 return res; 53 } 54 else if(lb < la) { 55 for(int i = lb - 1; i >= 0; i--) { 56 if(b[i] == '1' && a[la - (lb - i)] == '1') { 57 if(car == 1) 58 res = '1' + res; 59 else { 60 res = '0' + res; 61 car = 1; 62 } 63 } 64 else if(b[i] != a[la - (lb - i)]) { 65 if(car == 1) 66 res = '0' + res; 67 else 68 res = '1' + res; 69 } 70 else { 71 if(car == 1) { 72 res = '1' + res; 73 car = 0; 74 } 75 else 76 res = '0' + res; 77 } 78 } 79 for(int i = la - lb - 1; i >= 0; i--) { 80 if(a[i] == '1') { 81 if(car == 1) 82 res = '0' + res; 83 else 84 res = '1' + res; 85 } 86 else { 87 if(car == 1) { 88 res = '1' + res; 89 car = 0; 90 } 91 else 92 res = '0' + res; 93 } 94 } 95 if(car == 1) { 96 res = '1' + res; 97 } 98 return res; 99 } 100 } 101 };
