Stack Solutions

Stacks/Brackets Balanced.java

@@ -0,0 +1,93 @@
+public class Solution {
+
+	public static boolean checkBalanced(String exp) {
+		// Write your code here
+Stack st=new Stack();
+        boolean val=false;
+
+        for(int i=0;i<exp.length();i++){
+
+            if(exp.charAt(i)=='{' || exp.charAt(i)=='[' ||exp.charAt(i)=='('){
+                val=false;
+                st.push(exp.charAt(i));
+            }else if(exp.charAt(i)=='}' || exp.charAt(i)==']' || exp.charAt(i)==')'){
+                char c=st.pop();
+
+               // System.out.print(c);
+                if(c=='x'){
+                    return false;
+                }
+                if(exp.charAt(i)==')'){
+                    if(c=='('){
+                        val=true;
+                        continue;
+                    }//if there is any other brackets found set val to false;
+                    val=false;
+                    break;
+                }else if(exp.charAt(i)==']'){
+                    if(c=='['){
+                        val=true;
+                        continue;
+                    }
+                    val=false;
+                    break;
+                }else if(exp.charAt(i)=='}'){
+                    if(c=='{'){
+                        val=true;
+                        continue;
+                    }
+                    val=false;
+                    break;
+                }
+                else{
+                    val=false;
+                    break;
+                }
+
+            }
+        }
+        // ex- ([] here it will return true as the last it was found matched
+        //but there is still one element left in the stack and there is no
+        //brackets to match further so we keep condition if and only if
+        //top will go to null such that everything is matched
+        if(st.top!=null){
+            return false;
+        }
+        return val;
+	}
+}
+
+class Node{
+
+    char data;
+    Node next;
+    Node(char data){
+        this.data=data;
+    }
+}
+
+class Stack{
+
+    Node top;
+
+    public void push(char data){
+        Node newNode=new Node(data);
+        if(top==null){
+            newNode.next=null;
+            top=newNode;
+            return;
+        }
+        newNode.next=top;
+        top=newNode;
+    }
+
+    public char pop(){
+        if(top==null){
+           return 'x'; 
+        }
+        char c=top.data;
+        top=top.next;
+       // System.out.println(c);
+return c;
+	}
+}