Minimum Remove To Make Valid Parentheses

Author: charlesbuczel

1249_minimumRemoveToMakeValidParentheses.js

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+/**
+ * @param {string} s Input string containing letters and parentheses.
+ * @return {string} Possible solution to make string valid
+ * @summary Minimum Remove to Make Valid Parentheses {@link https://leetcode.com/problems/minimum-remove-to-make-valid-parentheses/}
+ * @description Given a string containing letters and parentheses, return valid string by removing minimum possible parentheses.
+ * Space O(1) - using 3 arrays, each of them can have up to n elements.
+ * Time O(n) - where n is input length.
+ */
+const minRemoveToMakeValid = s => {
+  const stack = [];
+  const toRemove = [];
+  const length = s.length;
+
+  for (let i = 0; i < length; i++) {
+    const char = s[i];
+
+    if (s[i] === ')') {
+      if (!stack.length) toRemove.push(i);
+      else stack.pop();
+    }
+    if (s[i] === '(') {
+      stack.push(i);
+    }
+  }
+
+  const solution = [];
+  for (let i = 0; i < length; i++) {
+    if (!stack.includes(i) && !toRemove.includes(i)) solution.push(s[i]);
+  }
+
+  return solution.join('');
+};