Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.
Example 1:
Input: n = 3
Output: [“((()))”,”(()())”,”(())()”,”()(())”,”()()()”]
Example 2:
Input: n = 1
Output: [“()”]
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| class Solution
{
public List<String> generateParenthesis(int n)
{
List<String> ans = new ArrayList<String>();
backtrack(ans, "", 0, 0, n);
return ans;
}
public void backtrack(List<String> ans, String cur, int open, int close, int max)
{
if(cur.length() == max * 2)
{
ans.add(cur);
}
if(open < max)
{
backtrack(ans, cur + "(", open + 1, close, max);
}
if(close < open)
{
backtrack(ans, cur + ")", open, close + 1, max);
}
}
}
|