Add missing problem 2116 to README table and fix row numbering

Author: Carlos Gutierrez

README.md

@@ -103,10 +103,11 @@ This repo tracks my journey solving LeetCode problems — not just code, but my
 | 72 | 1302 | [Deepest Leaves Sum](src/exercises/1302.deepest-leaves-sum.py) | Medium | Python |
 | 73 | 2016 | [Maximum Difference Between Increasing Elements](src/exercises/2016.maximum-difference-between-increasing-elements.py) | Easy | Python |
 | 74 | 2053 | [Kth Distinct String in an Array](src/exercises/2053.kth-distinct-string-in-an-array.py) | Easy | Python |
-| 75 | 2294 | [Partition Array Such That Maximum Difference Is K](src/exercises/2294.partition-array-such-that-maximum-difference-is-k.py) | Medium | Python |
-| 76 | 3442 | [Maximum Difference Between Even and Odd Frequency I](src/exercises/3442.maximum-difference-between-even-and-odd-frequency-i.py) | Easy | Python |
-| 77 | 3582 | [Generate Tag for Video Caption](src/exercises/3582.generate-tag-for-video-caption.py) | Easy | Python |
-| 78 | 3583 | [Count Special Triplets](src/exercises/3583.count-special-triplets.py) | Easy | Python |
+| 75 | 2116 | [Check if a Parentheses String Can Be Valid](src/exercises/2116.check-if-a-parentheses-string-can-be-valid.py) | Medium | Python |
+| 76 | 2294 | [Partition Array Such That Maximum Difference Is K](src/exercises/2294.partition-array-such-that-maximum-difference-is-k.py) | Medium | Python |
+| 77 | 3442 | [Maximum Difference Between Even and Odd Frequency I](src/exercises/3442.maximum-difference-between-even-and-odd-frequency-i.py) | Easy | Python |
+| 78 | 3582 | [Generate Tag for Video Caption](src/exercises/3582.generate-tag-for-video-caption.py) | Easy | Python |
+| 79 | 3583 | [Count Special Triplets](src/exercises/3583.count-special-triplets.py) | Easy | Python |
 
 ## 🛠️ Tools & Scripts
 - `create_missing_notes.sh`: Automatically creates missing note files for solved problems

src/exercises/2116.check-if-a-parentheses-string-can-be-valid.py

@@ -0,0 +1,57 @@
+from string import *
+from re import *
+from datetime import *
+from collections import *
+from heapq import *
+from bisect import *
+from copy import *
+from math import *
+from random import *
+from statistics import *
+from itertools import *
+from functools import *
+from operator import *
+from io import *
+from sys import *
+from json import *
+from builtins import *
+import string
+import re
+import datetime
+import collections
+import heapq
+import bisect
+import copy
+import math
+import random
+import statistics
+import itertools
+import functools
+import operator
+import io
+import sys
+import json
+from typing import *
+
+
+# @leet start
+class Solution:
+    def canBeValid(self, s: str, locked: str) -> bool:
+        if len(s) % 2 != 0:
+            return False
+        mo = 0
+        mxo = 0
+        for i in range(len(s)):
+            if locked[i] == "1":
+                mo = mo + 1 if s[i] == "(" else mo - 1
+                mxo = mxo + 1 if s[i] == "(" else mxo - 1
+            else:
+                mo -= 1
+                mxo += 1
+            if mxo < 0:
+                return False
+            mo = mo if mo > 0 else 0
+        return mo == 0
+
+
+# @leet end