[nb] Sync

exercises/dynamic-programming/22-generate-parenthesis/golang/main.go

@@ -0,0 +1,53 @@
+package main
+import (
+  "strings"
+  "container/list"
+)
+/*
+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: ["()"]
+ 
+  ()(); (())
+
+Constraints:
+
+1 <= n <= 8
+*/
+
+func rec(input []string, left int, right int, n int, ans *[]string) {
+
+  if len(input) == 2*n {
+    *ans = append(*ans, strings.Join(input, ""))
+    return
+  }
+  if left < n {
+    input = append(input, "(")
+    rec(input, left+1, right, n, ans)
+    input = input[0:len(input)-1]
+  }
+  if right < left {
+    input = append(input, ")")
+    rec(input, left, right+1, n, ans)
+    input = input[0:len(input)-1]
+  }
+}
+
+func generateParenthesis(n int) []string {
+  var output = make([]string, 2*n)
+  var input = make([]string, 2*n)
+  rec(input, 0, 0, n, &output)
+  return output
+}
+func main() {
+  generateParenthesis(3)
+}

exercises/dynamic-programming/22-generate-parenthesis/js/index.js

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+function generateParenthesis(n) {
+  const output = []
+  const rec = (input = [], left = 0, right = 0) => {
+    if (input.length === 2*n) {
+      output.push(input.join(''));
+      console.log('sol');
+      return
+    }
+    if (left < n) {
+      input.push('(');
+      console.log(input.join('') + ' l=' + left + ' r=' + right)
+      rec(input, left+1, right);
+      console.log('back left');
+      input.pop();
+    }
+
+    if (right < left) {
+      input.push(')');
+      console.log(input.join('') + ' l=' + left + ' r=' + right)
+      rec(input, left, right+1);
+      console.log('back right l=' + left);
+      input.pop();
+      console.log(input.join('') + ' l=' + left + ' r=' + right)
+    }
+  };
+  rec();
+  return output;
+}
+
+console.log(generateParenthesis(3));

exercises/dynamic-programming/22-generate-parenthesis/python/index.py

@@ -0,0 +1,25 @@
+from typing import List
+# ()()()
+# (())()
+# ((()))
+# ()(())
+# (()())
+
+def generateParenthesis(n: int) -> List[str]:
+    ans = []
+    def backtrack(S = [], left = 0, right = 0):
+        if len(S) == 2 * n:
+            ans.append("".join(S))
+            return
+        if left < n:
+            S.append("(")
+            backtrack(S, left+1, right)
+            S.pop()
+        if right < left:
+            S.append(")")
+            backtrack(S, left, right+1)
+            S.pop()
+    backtrack()
+    return ans
+
+generateParenthesis(3)