| 6 | |
| 7 | impl Solution { |
| 8 | pub fn add_binary(a: String, b: String) -> String { |
| 9 | let a = a.chars().collect::<Vec<char>>(); |
| 10 | let b = b.chars().collect::<Vec<char>>(); |
| 11 | let mut res = vec!['0'; usize::max(a.len(), b.len()) + 1]; |
| 12 | let mut carry = false; |
| 13 | for i in (0..res.len()).rev() { |
| 14 | let offset = res.len() - i; |
| 15 | let p = if a.len() < offset { None } else { Some(a[a.len() - offset]) }; |
| 16 | let q = if b.len() < offset { None } else { Some(b[b.len() - offset]) }; |
| 17 | match (p, q) { |
| 18 | (Some(x), Some(y)) => { |
| 19 | match (x, y) { |
| 20 | ('0', '1') | ('1', '0') => { |
| 21 | if !carry { res[i] = '1'; carry = false } |
| 22 | } |
| 23 | ('0', '0') => { |
| 24 | if carry { res[i] = '1'; carry = false } |
| 25 | } |
| 26 | ('1', '1') => { |
| 27 | if carry { res[i] = '1' } |
| 28 | carry = true |
| 29 | } |
| 30 | _ => unreachable!() |
| 31 | } |
| 32 | } |
| 33 | (Some(x), None) | (None, Some(x)) => { |
| 34 | if carry && x == '0' { res[i] = '1'; carry = false } |
| 35 | else if !carry { res[i] = x } |
| 36 | } |
| 37 | _ => { if carry { res[i] = '1'; carry = false } } |
| 38 | } |
| 39 | |
| 40 | } |
| 41 | if res[0] == '0' { res.remove(0); } |
| 42 | res.iter().collect() |
| 43 | } |
| 44 | } |
| 45 | |
| 46 | #[cfg(test)] |