C++ program to check whether given string is bad or not

Suppose we have a string S with n characters. S contains lowercase English letters and ')' characters. The string is bad, if the number of characters ')' at the end is strictly greater than the number of remaining characters. We have to check whether S is bad or not.

So, if the input is like S = "fega))))))", then the output will be True, because this is bad as there are 4 letters and 6 ')'s.

Steps

To solve this, we will follow these steps −

ans := 0
n := size of S
i := n - 1
while (i >= 0 and S[i] is same as ')'), do:
   (decrease i by 1)
z := n - 1 - i
ans := 2 * z - n
if ans > 0, then:
   return true
Otherwise
   return false

Example

Let us see the following implementation to get better understanding −

#include <bits/stdc++.h>
using namespace std;

bool solve(string S) {
   int ans = 0;
   int n = S.size();
   int i = n - 1;
   while (i >= 0 && S[i] == ')')
      i--;
   int z = n - 1 - i;
   ans = 2 * z - n;
   if (ans > 0)
      return true;
   else
      return false;
}
int main() {
   string S = "fega))))))";
   cout << solve(S) << endl;
}