Remove the minimum number of invalid parentheses in order to make the input string valid. Return all possible results.
Note: The input string may contain letters other than the parentheses ( and ).
Example 1:
Input: "()())()" Output: ["()()()", "(())()"]
Example 2:
Input: "(a)())()" Output: ["(a)()()", "(a())()"]
Example 3:
Input: ")("
Output: [""]
删除最小数量的无效括号，使得输入的字符串有效，返回所有可能的结果。
说明: 输入可能包含了除 ( 和 ) 以外的字符。
示例 1:
输入: "()())()" 输出: ["()()()", "(())()"]
示例 2:
输入: "(a)())()" 输出: ["(a)()()", "(a())()"]
示例 3:
输入: ")("
输出: [""]
20ms
1 class Solution { 2 func removeInvalidParentheses(_ s: String) -> [String] { 3 var paths = [String]() 4 dfs(&paths, Array(s), 0, 0, ("(", ")")) 5 return paths 6 } 7 8 fileprivate func dfs(_ paths: inout [String], _ s: [Character], _ lastValid: Int, _ lastRight: Int, _ parens: (Character, Character)) { 9 var count = 0, s = s 10 11 for i in lastValid ..< s.count { 12 if s[i] == parens.0 { 13 count += 1 14 } 15 16 if s[i] == parens.1 { 17 count -= 1 18 } 19 20 if count < 0 { 21 for j in lastRight ... i { 22 guard s[j] == parens.1 else { 23 continue 24 } 25 26 guard j == 0 || s[j] != s[j - 1] || j == lastRight else { 27 continue 28 } 29 30 dfs(&paths, Array(s[0 ..< j] + s[j + 1 ..< s.count]), i, j, parens) 31 } 32 return 33 } 34 } 35 36 if parens.0 == "(" { 37 dfs(&paths, s.reversed(), 0, 0, (")", "(")) 38 } else { 39 paths.append(String(s.reversed())) 40 } 41 } 42 }
40ms
1 class Solution { 2 func removeInvalidParentheses(_ s: String) -> [String] { 3 4 var res = [String]() 5 var repeated = Set<String>() 6 removeRight(s, &res, &repeated) 7 return res 8 } 9 10 func removeRight(_ s : String, _ res : inout [String], _ repeated : inout Set<String>) { 11 let sArr = Array(s) 12 var count = 0 13 for i in 0..<sArr.count { 14 let c = sArr[i] 15 if c == "(" { 16 count += 1 17 }else if c == ")" { 18 count -= 1 19 } 20 21 if count < 0 { 22 for j in 0...i where sArr[j] == ")" { 23 let r = String(sArr[0..<j] + sArr[j+1..<sArr.count]) 24 if repeated.contains(r) { 25 continue 26 } 27 repeated.insert(r) 28 removeRight(r, &res, &repeated) 29 } 30 return 31 } 32 } 33 if count == 0 { 34 res.append(s) 35 return 36 } 37 38 removeLeft(s, &res, &repeated) 39 } 40 41 func removeLeft(_ s : String, _ res : inout [String], _ repeated : inout Set<String>) { 42 let sArr = Array(s) 43 var count = 0 44 for i in stride(from: sArr.count-1, to: -1, by: -1) { 45 let c = sArr[i] 46 if c == ")" { 47 count += 1 48 }else if c == "("{ 49 count -= 1 50 } 51 52 if count < 0 { 53 for j in stride(from: sArr.count-1, to: i-1, by: -1) where sArr[j] == "(" { 54 let r = String(sArr[0..<j] + sArr[j+1..<sArr.count]) 55 if repeated.contains(r) { 56 continue 57 } 58 repeated.insert(r) 59 removeLeft(r, &res, &repeated) 60 } 61 return 62 } 63 } 64 res.append(s) 65 } 66 }
84ms
1 class Solution { 2 func isValid(_ str:String) -> Bool { 3 4 var left = 0 5 6 for char in str { 7 8 if char == Character("(") { 9 10 left += 1 11 } 12 13 if char == Character(")") { 14 15 left -= 1 16 } 17 18 if left < 0 { 19 20 return false 21 } 22 } 23 24 return left == 0 25 } 26 27 func removeInvalidParentheses(_ s: String) -> [String] { 28 29 var results:[String] = [] 30 31 if isValid(s) { 32 33 return [s] 34 } 35 36 let mustRemove = findInvalid(s) 37 38 removeAndCheck(s, start:0, left: mustRemove.left, right: mustRemove.right, &results) 39 40 return results 41 } 42 43 func removeAndCheck(_ str:String, start:Int, left:Int, right:Int, _ results:inout [String]) { 44 45 if left == 0 && right == 0 { 46 47 if isValid(str) { 48 49 results.append(str) 50 } 51 52 return 53 } 54 55 for i in start..<str.count { 56 57 let index = str.index(str.startIndex, offsetBy: i) 58 59 let next = str.index(after: index) 60 61 if i != start { 62 63 let prev = str.index(before: index) 64 65 if str[index] == str[prev] { 66 67 continue 68 } 69 } 70 71 let char = str[index] 72 73 if char == Character("(") && left > 0 { 74 75 let substr = String(str[str.startIndex..<index] + str[next...]) 76 77 removeAndCheck(substr, start:i, left: left - 1, right: right , &results) 78 } 79 80 if char == Character(")") && right > 0 { 81 82 let substr = String(str[str.startIndex..<index] + str[next...]) 83 84 removeAndCheck(substr, start:i, left: left, right: right - 1, &results) 85 } 86 } 87 } 88 89 func findInvalid(_ str:String) -> (left:Int, right:Int) { 90 91 var cnt1 = 0, cnt2 = 0 92 93 for char in str { 94 95 if char == Character("(") { 96 97 cnt1 += 1 98 } 99 100 if cnt1 == 0 { 101 102 if char == Character(")") { 103 104 cnt2 += 1 105 } 106 } 107 else { 108 109 if char == Character(")") { 110 111 cnt1 -= 1 112 } 113 } 114 } 115 116 return (cnt1, cnt2) 117 } 118 }