[Leetcode] 022. Generate parentheses (Medium) (C++/python)

Index: [Leetcode] leetcode key index (C++/JAVA/PYTHON/SQL)
Github:https://github.com/illuz/leetcode

022.generate_parentheses (Medium) links：

Title: https://oj.leetcode.com/problems/generate-parentheses/
Code (GitHub): Https://github.com/illuz/leetcode

Test Instructions：

Produces all valid strings with n-brackets.

Analysis：

1. Using DFS can be done quickly, can add ' (' Add ' (', can add ') ' Add ') '. (The following C + + implementation)
2. There is also a very witty way to write a short DFS. (Java Implementation)
3. For DFS can be memory, with space to change time. (Python Implementation)

Code：

C++:

Class Solution {private:string tmp;void dfs (vector<string> &v, int pos, int n, int used) {if (pos = = n * 2) {Cou T << tmp << endl;v.push_back (TMP); return;} if (used < n) {tmp.push_back (' (');d FS (V, POS + 1, N, used + 1); Tmp.pop_back ();} if (used * 2 > POS) {tmp.push_back (') ');d FS (V, POS + 1, n, used); Tmp.pop_back ();}} Public:    vector<string> generateparenthesis (int n) {vector<string> res;if (n = = 0) return res;tmp = "";d FS (res, 0, N, 0); return res;    }};

Java:

public class Solution {public    list<string> generateparenthesis (int n) {        list<string> ret = new Array List<string> (), inner, outter;        if (n = = 0) {            ret.add ("");            return ret;        }        if (n = = 1) {            Ret.add ("()");            return ret;        }        for (int i = 0; i < n; ++i) {            inner = generateparenthesis (i);            Outter = Generateparenthesis (N-i-1);            for (int j = 0, J < inner.size (); ++j) {for                (int k = 0; k < outter.size (); ++k) {                    Ret.add ("(" + inner.get (j) + ")" + Outter.get (k));        }} return ret;    }}

Python:

Class solution:    # @param an integer    # @return A list    of the string def generateparenthesis (self, N):        DP = {0: [""], 1: ["()"]}        def memorial_dfs (n):            if n not in DP:                dp[n] = [] for                I in range (n): for                    inner in Memor Ial_dfs (i): for                        outter in Memorial_dfs (N-i-1):                            dp[n].append (' (' + inner + ') ' + outter ')            return DP[N]
   return Memorial_dfs (N)

[Leetcode] 022. Generate parentheses (Medium) (C++/python)