[nb] Commit

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

@@ -1,17 +1,30 @@
 function generateParenthesis(n) {
-  if (n == 1) {
-    return ['()'];
-  }
+  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 (n == 2) {
-    return ['()()', '(())'];
-  }
-
-  const input = [];
-  for (i = 0; i < n; i++) {
-    input.push('()');
-  }
-
-  for(i = 0; i < n; i++; i++) {
-  }
+    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));