Check if the bracket sequence can be balanced with at most one change in the position of a bracket (original) (raw)

Last Updated : 13 Jul, 2022

Given an unbalanced bracket sequence as a string str, the task is to find whether the given string can be balanced by moving at most one bracket from its original place in the sequence to any other position.
Examples:

Input: str = ")(()"
Output: Yes
As by moving s[0] to the end will make it valid.
"(())"
Input: str = "()))(()"
Output: No

Approach: Consider X as a valid bracket then definitely (X) is also valid. If X is not valid and can be balanced with just one change of position in some bracket then it must be of type X = ")(" where ')' has been placed before '('.
Now, X can be replaced with (X) as it will not affect the balanced nature of X. The new string becomes X = "()()" which is balanced.
Hence, if (X) is balanced then we can say that X can be balanced with at most one change in the position of some bracket.
Below is the implementation of the above approach:

C++ `

// CPP implementation of the approach #include <bits/stdc++.h> using namespace std;

// Function that returns true if the sequence // can be balanced by changing the // position of at most one bracket bool canBeBalanced(string s, int n) { // Odd length string can // never be balanced if (n % 2 == 1) return false;

// Add '(' in the beginning and ')'
// in the end of the string
string k = "(";
k += s + ")";

vector<string> d;
int cnt = 0;

for (int i = 0; i < k.length(); i++)
{
    // If its an opening bracket then
    // append it to the temp string
    if (k[i] == '(')
        d.push_back("(");

    // If its a closing bracket
    else
    {
        // There was an opening bracket
        // to match it with
        if (d.size() != 0)
            d.pop_back();

        // No opening bracket to
        // match it with
        else
            return false;
    }
}

// Sequence is balanced
if (d.empty())
    return true;
return false;

}

// Driver Code int main(int argc, char const *argv[]) { string s = ")(()"; int n = s.length();

(canBeBalanced(s, n)) ? cout << "Yes" 
              << endl : cout << "No" << endl;
return 0;

}

// This code is contributed by // sanjeev2552

Java

// Java implementation of the approach import java.util.Vector;

class GFG {

// Function that returns true if the sequence
// can be balanced by changing the
// position of at most one bracket
static boolean canBeBalanced(String s, int n)
{

    // Odd length string can
    // never be balanced
    if (n % 2 == 1)
        return false;

    // Add '(' in the beginning and ')'
    // in the end of the string
    String k = "(";
    k += s + ")";
    Vector<String> d = new Vector<>();

    for (int i = 0; i < k.length(); i++)
    {

        // If its an opening bracket then
        // append it to the temp string
        if (k.charAt(i) == '(')
            d.add("(");

        // If its a closing bracket
        else 
        {

            // There was an opening bracket
            // to match it with
            if (d.size() != 0)
                d.remove(d.size() - 1);

            // No opening bracket to
            // match it with
            else
                return false;
        }
    }

    // Sequence is balanced
    if (d.isEmpty())
        return true;
    return false;
}

// Driver Code
public static void main(String[] args) 
{
    String s = ")(()";
    int n = s.length();

    if (canBeBalanced(s, n))
        System.out.println("Yes");
    else
        System.out.println("No");
}

}

// This code is contributed by // sanjeev2552

Python3

Python3 implementation of the approach

Function that returns true if the sequence

can be balanced by changing the

position of at most one bracket

def canBeBalanced(s, n):

# Odd length string can 
# never be balanced
if n % 2 == 1:
    return False

# Add '(' in the beginning and ')' 
# in the end of the string
k = "("
k = k + s+")"
d = []
count = 0
for i in range(len(k)):

    # If its an opening bracket then 
    # append it to the temp string
    if k[i] == "(":
        d.append("(")

    # If its a closing bracket
    else:

        # There was an opening bracket 
        # to match it with
        if len(d)!= 0:
            d.pop()

        # No opening bracket to 
        # match it with
        else:
            return False

# Sequence is balanced
if len(d) == 0:
    return True
return False

Driver code

S = ")(()" n = len(S) if(canBeBalanced(S, n)): print("Yes") else: print("No")

C#

// C# implementation of the approach using System; using System.Collections.Generic;

class GFG {

// Function that returns true if the sequence
// can be balanced by changing the
// position of at most one bracket
static bool canBeBalanced(string s, int n)
{

    // Odd length string can
    // never be balanced
    if (n % 2 == 1)
        return false;

    // Add '(' in the beginning and ')'
    // in the end of the string
    string k = "(";
    k += s + ")";
    List<string> d = new List<string>();

    for (int i = 0; i < k.Length; i++)
    {

        // If its an opening bracket then
        // append it to the temp string
        if (k[i] == '(')
            d.Add("(");

        // If its a closing bracket
        else
        {

            // There was an opening bracket
            // to match it with
            if (d.Count != 0)
                d.RemoveAt(d.Count - 1);

            // No opening bracket to
            // match it with
            else
                return false;
        }
    }

    // Sequence is balanced
    if (d.Count == 0)
        return true;
    return false;
}

// Driver Code
public static void Main() 
{
    string s = ")(()";
    int n = s.Length;

    if (canBeBalanced(s, n))
        Console.Write("Yes");
    else
        Console.Write("No");
}

}

// This code is contributed by // mohit kumar 29

JavaScript

`

Time Complexity : O(n) ,where n is size of given string

Space Complexity : O(n)