solves minimum removals to make valid parentheses inj java

Author: anishLearnsToCode

README.md

@@ -504,6 +504,7 @@
 | 1232 | [Check If It Is A Straight Line](https://leetcode.com/problems/check-if-it-is-a-straight-line)                                                            |                                                            [![Java](assets/java.png)](src/CheckIfItIsASStraightLine.java)                                                            |                                                                                                                                   |
 | 1237 | [Find Positive Integer Solutions for a Given Equation](https://leetcode.com/problems/find-positive-integer-solution-for-a-given-equation)                 |                                                                                                                                                                                      |                                                                                                                                   |
 | 1243 | 🔒 [Array Transformation](https://leetcode.com/problems/array-transformation)                                                                             |                                                                                                                                                                                      |                                                                                                                                   |
+| 1249 | [Minimum Remove to Make Valid Parentheses](https://leetcode.com/problems/minimum-remove-to-make-valid-parentheses)                                        |                                                       [![Java](assets/java.png)](src/MinimumRemoveToMakeValidParentheses.java)                                                       |                                                                                                                                   |
 | 1252 | [Cells With Odd Values In Matrix](https://leetcode.com/problems/cells-with-odd-values-in-a-matrix)                                                        |                                                           [![Java](assets/java.png)](src/CellsWithOddValuesInMatrix.java)                                                            |                                                                                                                                   |
 | 1260 | [Shift 2D Grid](https://leetcode.com/problems/shift-2d-grid)                                                                                              |                                                                   [![Java](assets/java.png)](src/Shift2DGrid.java)                                                                   |                                                                                                                                   |
 | 1266 | [Minimum Time Visiting All Points](https://leetcode.com/problems/minimum-time-visiting-all-points)                                                        |                                                          [![Java](assets/java.png)](src/MinimumTimeVisitingAllPoints.java)                                                           |                                                                                                                                   |

src/MinimumRemoveToMakeValidParentheses.java

@@ -0,0 +1,44 @@
+// https://leetcode.com/problems/minimum-remove-to-make-valid-parentheses
+// T: O(n)
+// S: O(n)
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.Stack;
+
+public class MinimumRemoveToMakeValidParentheses {
+    private static final record OpeningBrace(int index) { }
+
+    public String minRemoveToMakeValid(String s) {
+        final Stack<OpeningBrace> stack = new Stack<>();
+        final List<Integer> extraClosingBraceIndices = new ArrayList<>();
+        char c;
+        for (int i = 0 ; i < s.length() ; i++) {
+            c = s.charAt(i);
+            if (c == ')') {
+                if (!stack.isEmpty()) {
+                    stack.pop();
+                } else extraClosingBraceIndices.add(i);
+            } else if (c == '(') stack.push(new OpeningBrace(i));
+        }
+        final Set<Integer> errorIndices = compileErrorIndicesFrom(extraClosingBraceIndices, stack);
+        StringBuilder result = new StringBuilder();
+        for (int i = 0; i < s.length() ; i++) {
+            if (!errorIndices.contains(i)) {
+                result.append(s.charAt(i));
+            }
+        }
+        return result.toString();
+    }
+
+    private Set<Integer> compileErrorIndicesFrom(List<Integer> wrongClosingBraces, Stack<OpeningBrace> openingBraces) {
+        Set<Integer> result = new HashSet<>();
+        while (!openingBraces.isEmpty()) {
+            result.add(openingBraces.pop().index);
+        }
+        result.addAll(wrongClosingBraces);
+        return result;
+    }
+}