22. 括号生成 @Python @Go

原题

https://leetcode.cn/problems/generate-parentheses/description/

思路

回溯法

复杂度

时间：O(n)
空间：O(n)

Python代码

class Solution:
    def generateParenthesis(self, n: int) -> List[str]:
        ans = []

        def dfs(left, right, path):
            if left == n and right == n:
                ans.append(path)
                return
            if right > left or left > n or right > n:
                return
            dfs(left + 1, right, path + "(")
            dfs(left, right + 1, path + ")")

        dfs(0, 0, "")
        return ans        

Go代码

func generateParenthesis(n int) []string {
	ans := []string{}
	// 匿名函数
	var dfs func(int, int, string)
	dfs = func(left int, right int, path string) {
		if left == n && right == n {
			ans = append(ans, path)
			return
		}
		if right > left || left > n || right > n {
			return
		}
		dfs(left+1, right, path+"(")
		dfs(left, right+1, path+")")
	}
	dfs(0, 0, "")
	return ans
}