Merge pull request kothariji#121 from MrTwinkleSharma/master

Application of Stack (Balanced Brackets)

Author: kothariji

Stack/(HACKERRANK) Balanced Brackets.cpp

@@ -0,0 +1,71 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+//This ALgorithm checks whether all the brackets of string are balanced or not
+//Go to Hackerrank "Balanced Brackets" Question to see more description
+
+// Complete the isBalanced function below.
+string isBalanced(string text) {
+    //creating a stack to store opening brackets only
+    stack <char> opening_brackets_stack;
+    
+    //Looping till string end
+    for (int position = 0; position < text.length(); ++position) {
+        char next = text[position];
+        //storing the character in a next named char
+        
+        //if it is open bracket then simpy push it in stack
+        if (next == '(' || next == '[' || next == '{') {
+            opening_brackets_stack.push(next);
+        }
+        
+        //if closed then check two conditions
+        if (next == ')' || next == ']' || next == '}') {
+            
+             char last;
+             //if the stack is empty means brackets will be unbalanced if not then it get the last bracket of stack
+             if(!opening_brackets_stack.empty())
+             {
+                 last = opening_brackets_stack.top();
+             }
+            else  return "NO";
+           
+            //if last matches with next then pop that opening bracket otherwise return NO
+            if ((last == '(' && next== ')') || (last == '[' && next == ']') || (last == '{' && next== '}'))
+             {
+                  opening_brackets_stack.pop();
+                  continue;
+            }          
+            else
+            return "NO";      
+        }
+    }
+    
+    //At the end if nothing is returned from loop then now check whether the stack is empty or not if yes then it means, string was balanced.
+    if(opening_brackets_stack.empty())
+    return "YES";
+    else
+    return "NO";
+}
+
+int main()
+{
+    ofstream fout(getenv("OUTPUT_PATH"));
+
+    int t;
+    cin >> t;
+    cin.ignore(numeric_limits<streamsize>::max(), '\n');
+
+    for (int t_itr = 0; t_itr < t; t_itr++) {
+        string s;
+        getline(cin, s);
+
+        string result = isBalanced(s);
+
+        fout << result << "\n";
+    }
+
+    fout.close();
+
+    return 0;
+}