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Generate Parentheses in Python
Suppose we have a value n. We have to generate all possible well-formed parentheses where n number of opening and closing parentheses are present. So if the value of n = 3, then the parentheses set will be ["()()()","()(())","(())()","(()())","((()))"]
To solve this, we will follow these steps −
- Define method called genParenthesisRec(). This takes left, right, temp string and result array. initially result array is empty
- The function genParenthesisRec, will work like below
- if left = 0 and right := 0, then insert temp into result, and return
- if left > 0
- getParenthesisRec(left – 1, right, temp + “(”, result)
- if right > left
- getParenthesisRec(left, right – 1, temp + “)”, result)
Example(Python)
Let us see the following implementation to get a better understanding −
class Solution(object):
def generateParenthesis(self, n):
"""
:type n: int
:rtype: List[str]
"""
result = []
self.generateParenthesisUtil(n,n,"",result)
return result
def generateParenthesisUtil(self, left,right,temp,result):
if left == 0 and right == 0:
result.append(temp)
return
if left>0:
self.generateParenthesisUtil(left-1,right,temp+'(',result)
if right > left:
self.generateParenthesisUtil(left, right-1, temp + ')', result)
ob = Solution()
print(ob.generateParenthesis(4))Input
4
Output
["(((())))", "((()()))", "((())())", "((()))()", "(()(()))", "(()()())", "(()())()", "(())(())", "(())()()", "()((()))", "()(()())", "()(())()", "()()(())", "()()()()"]
Updated on: 27-Apr-2020
2K+ Views
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