|
| 1 | +/** |
| 2 | + * [301] Remove Invalid Parentheses |
| 3 | + * |
| 4 | + * Remove the minimum number of invalid parentheses in order to make the input string valid. Return all possible results. |
| 5 | + * |
| 6 | + * Note: The input string may contain letters other than the parentheses ( and ). |
| 7 | + * |
| 8 | + * Example 1: |
| 9 | + * |
| 10 | + * |
| 11 | + * Input: "()())()" |
| 12 | + * Output: ["()()()", "(())()"] |
| 13 | + * |
| 14 | + * |
| 15 | + * Example 2: |
| 16 | + * |
| 17 | + * |
| 18 | + * Input: "(a)())()" |
| 19 | + * Output: ["(a)()()", "(a())()"] |
| 20 | + * |
| 21 | + * |
| 22 | + * Example 3: |
| 23 | + * |
| 24 | + * |
| 25 | + * Input: ")(" |
| 26 | + * Output: [""] |
| 27 | + * |
| 28 | + */ |
| 29 | +pub struct Solution {} |
| 30 | + |
| 31 | +// submission codes start here |
| 32 | + |
| 33 | +// 1. Calculate the number of misplaced left parenthese and right parenthese |
| 34 | +// 2. DFS the string to find the all possible removing policy |
| 35 | +use std::collections::HashSet; |
| 36 | +impl Solution { |
| 37 | + pub fn remove_invalid_parentheses(s: String) -> Vec<String> { |
| 38 | + let (mut left, mut right) = (0, 0); |
| 39 | + let mut chs: Vec<char> = s.chars().collect(); |
| 40 | + for &c in chs.iter() { |
| 41 | + if c == '(' { |
| 42 | + left += 1; |
| 43 | + } else if c == ')' { |
| 44 | + if left > 0 { |
| 45 | + left -= 1; |
| 46 | + } else { |
| 47 | + right += 1; |
| 48 | + } |
| 49 | + } |
| 50 | + } |
| 51 | + |
| 52 | + // Now, the number of left and right parentheses are 'left' and 'right' |
| 53 | + let mut res: HashSet<String> = HashSet::new(); |
| 54 | + let mut seed: Vec<char> = Vec::new(); |
| 55 | + Solution::helper(&chs, 0, 0, left, right, &mut seed, &mut res); |
| 56 | + res.into_iter().collect() |
| 57 | + } |
| 58 | + |
| 59 | + fn helper(chs: &Vec<char>, idx: usize, left: i32, l_remain: i32, r_remain: i32, exp: &mut Vec<char>, res: &mut HashSet<String>) { |
| 60 | + if idx >= chs.len() { |
| 61 | + if left == 0 { |
| 62 | + res.insert(exp.iter().collect()); |
| 63 | + } |
| 64 | + return |
| 65 | + } |
| 66 | + if chs[idx] == '(' { |
| 67 | + if l_remain > 0 { |
| 68 | + Solution::helper(chs, idx+1, left, l_remain-1, r_remain, &mut exp.clone(), res); |
| 69 | + } |
| 70 | + exp.push('('); |
| 71 | + Solution::helper(chs, idx+1, left+1, l_remain, r_remain, exp, res); |
| 72 | + } else if chs[idx] == ')' { |
| 73 | + if r_remain > 0 { |
| 74 | + Solution::helper(chs, idx+1, left, l_remain, r_remain-1, &mut exp.clone(), res); |
| 75 | + } |
| 76 | + if left > 0 { |
| 77 | + exp.push(')'); |
| 78 | + Solution::helper(chs, idx+1, left-1, l_remain, r_remain, exp, res); |
| 79 | + } |
| 80 | + } else { |
| 81 | + exp.push(chs[idx]); |
| 82 | + Solution::helper(chs, idx+1, left, l_remain, r_remain, exp, res); |
| 83 | + } |
| 84 | + } |
| 85 | +} |
| 86 | + |
| 87 | +// submission codes end |
| 88 | + |
| 89 | +#[cfg(test)] |
| 90 | +mod tests { |
| 91 | + use super::*; |
| 92 | + |
| 93 | + #[test] |
| 94 | + fn test_301() { |
| 95 | + assert_eq!(Solution::remove_invalid_parentheses("()())()".to_owned()), vec_string!["(())()", "()()()"]); |
| 96 | + assert_eq!(Solution::remove_invalid_parentheses("(a)())()".to_owned()), vec_string!["(a)()()", "(a())()"]); |
| 97 | + } |
| 98 | +} |
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