Minimum Insertions to Balance a Parentheses String LeetCode solution in C++

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class Solution {
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 public:
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  int minInsertions(string s) {
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    stack<char> v;
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    int ans = 0;
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    for (int i = 0; i < s.size(); i++) {
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      if (s[i] == '(')
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        v.push(s[i]);
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      else {
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        if (s[i] == ')' && i < s.size() && s[i + 1] == ')') {
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          if (!v.empty())
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            v.pop();
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          else
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            ans++;
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          i++; // because we considered i+1 in this case
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        } else if (s[i] == ')' && i < s.size() && s[i + 1] != ')') {
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          if (!v.empty()) {
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            v.pop();
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            ans++;
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          } else
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            ans += 2;
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        }
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      }
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    }
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    if (v.empty()) return ans;
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    return v.size() * 2 + ans;
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  }
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};