We use cookies to ensure you have the best browsing experience on our website. Please read our cookie policy for more information about how we use cookies.
  1. Prepare
  2. Data Structures
  3. Stacks
  4. Balanced Brackets
  5. Discussions

Balanced Brackets

Sort by

recency

|

1630 Discussions

|

  • rajivaiyer
     + 0 comments

    Fairly simple Stack based problem. Nothing too complex.

    Here's my Java 8 solution, passing all test cases, for Max Score of 25:

    class Result {
    
    private static final String B_ROUND  = "()";
    private static final String B_SQUARE = "[]";
    private static final String B_CURLY  = "{}";
    
    private static String getBracketType(Character bracketCh) {
        return getBracketType("" + bracketCh);
    }
    
    private static String getBracketType(String bracketStr) {
        switch(bracketStr) {
            case "(":
            case ")":
                return B_ROUND;
            case "[":
            case "]":
                return B_SQUARE;
            case "{":
            case "}":
                return B_CURLY;
            default:
                return "";
        }
    }
    
    private static Character getExpectedOpenBracketCh(String curBracketType) {
        switch (curBracketType) {
            case B_ROUND:
                return '(';
            case B_SQUARE:
                return '[';
            case B_CURLY:
                return '{';
            default:
                return 'd';
        }
    }
    
    /*
     * Complete the 'isBalanced' function below.
     *
     * The function is expected to return a STRING.
     * The function accepts STRING s as parameter.
     */

    public static String isBalanced(String s) {
        // Write your code here
        Stack<Character> bracketsStack = new Stack<>();

        System.err.println(""); System.err.println("");
        System.err.println("s=" + s);

        for (int sIdx = 0 ; sIdx < s.length() ; sIdx++) {

            Character sCh = s.charAt(sIdx);
            String curBracketType = getBracketType(sCh);
            
            // System.err.println("sIdx=" + sIdx + " | sCh=" + sCh + " | " +
            //                    "curBracketType=" + curBracketType);

            switch(sCh) {
                case '(':
                case '[':
                case '{':
                    bracketsStack.push(sCh);
                    break;

                case ')':
                case ']':
                case '}':
                
                    if (bracketsStack.isEmpty()) {
                        return "NO";
                    }

                    Character peekStackTopBracket =
                                  bracketsStack.peek();

                    Character expectedOpenBracket = 
                                  getExpectedOpenBracketCh(curBracketType);
                                  
                    // System.err.println("peekStackTopBracket=" + 
                    //                    peekStackTopBracket + " | " +
                    //                    "expectedOpenBracket=" + 
                    //                    expectedOpenBracket);

                    if (peekStackTopBracket != expectedOpenBracket) {
                        return "NO";
                    }

                    bracketsStack.pop();
                    break;
            }
        }
        
        if (!bracketsStack.isEmpty()) {
            return "NO";
        }

        return "YES";
    }

}

  • yousefbahaa487
     + 0 comments

    C++: its run correctly in my compiler but when i run it on hackerrank it shows me that all test cases are wrong, and i try all of the test cases and it run correct on my compiler, i dont know what to do!!

    #include<bits/stdc++.h>
using namespace std;
void fastIO()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
}
int main()
{
    fastIO();
    int t;
    cin >> t;
    cin.ignore();
    
    while (t--) {
        stack<char>st;
        bool balanced= 1;
        string line;
        getline(cin, line);
        
        for (int i = 0; i < line.length(); i++)
        {
            if(line[i]=='('||line[i]=='{'||line[i]=='[') {
                st.push(line[i]);
            }
            else if(line[i]==')'||line[i]=='}'||line[i]==']')
            {
                if(!st.empty())
                {
                    if(line[i]==')'&&st.top()=='(')st.pop();
                    else if(line[i]==']'&&st.top()=='[')st.pop();
                    else if(line[i]=='}'&&st.top()=='{')st.pop();
                    else {
                        
                        balanced=0;
                        break; 
                    }
                }
            }
        }
        
        if(balanced==0||!st.empty()){
            cout<<"No"<<"\n";
            balanced=1;
        }
        else cout<<"Yes"<<"\n";
        
    }
    return 0;
}
        
    }
    return 0;
}

  • awadallayossef
     + 0 comments
    def isBalanced(s):
    closeToOpen = { ")" : "(", "]" : "[", "}" : "{" }
    Stack = []

    for x in s:
        if x in closeToOpen:
            if Stack and Stack[-1] == closeToOpen[x]:
                Stack.pop()
            else:
                return "NO"
        else:
            Stack.append(x)

    return "NO" if len(Stack) > 0 else "YES"

  • jain_sushmit9
     + 0 comments

    C++:

    string isBalanced(string s) { std::map m {{'(',')'}, {'{','}'}, {'[',']'}}; std::stack st;

    if (s.length() %2 != 0)
    return("NO");
for (int i=0;i<s.length();i++)
{
    auto it = m.find(s[i]);
    if(it != m.end())
    {
        st.push(s[i]);
    }
    else
    {
        if(st.empty())
        {
            return("NO");
        }
        if(m[st.top()] == s[i])
            st.pop();
        else
            return("NO");
    }
}
if(st.empty())
    return("YES");
else    
    return("NO");

    }

  • joosx2000
     + 0 comments

    Simple java solution in O(n) 100%:

    public static String isBalanced(String s) {
    Stack<Character> stack = new Stack<>();
    Map<Character, Character> dict = Map.of('{','}', '[',']', '(',')');

    for (char c : s.toCharArray()) {
        if (dict.containsKey(c)) stack.push(dict.get(c));
        else if (stack.isEmpty() || c != stack.pop()) return "NO";
    }

    return stack.isEmpty() ? "YES" : "NO";
}