Add Duplicate Brackets (#2766)

DataStructures/Stacks/DuplicateBrackets.java

@@ -0,0 +1,45 @@
+//  1. You are given a string exp representing an expression.
+// 2. Assume that the expression is balanced  i.e. the opening and closing brackets match with each other.
+// 3. But, some of the pair of brackets maybe extra/needless. 
+// 4. You are required to print true if you detect extra brackets and false otherwise.
+
+// e.g.'
+// ((a + b) + (c + d)) -> false
+// (a + b) + ((c + d)) -> true
+
+
+import java.io.*;
+import java.util.*;
+
+public class DuplicateBrackets {
+
+    public static boolean check(String str){
+        Stack<Character> st = new Stack<>();
+        
+        for(int i=0;i<str.length();i++){
+            char ch = str.charAt(i);
+            if(ch==')'){
+                if(st.peek()=='('){
+                    return true;
+                }else{
+                    while(st.size()>0 && st.peek()!='('){
+                        st.pop();
+                    }
+                    st.pop();
+                }
+                
+            }else{
+                st.push(ch);
+            }
+            // System.out.println(st);
+        }
+        return false;
+    }
+
+    public static void main(String[] args) throws Exception {
+        Scanner sc = new Scanner(System.in);
+        String str = sc.nextLine();
+        System.out.println(check(str));
+    }
+
+}