enh(CPlusPlus): balanced-parenthesis (#380)

algorithms/CPlusPlus/Stacks/balanced-parenthesis.cpp

@@ -1,43 +1,55 @@
+/*
+Program to check whether the Parenthesis are balanced or not
+*/
 #include<bits/stdc++.h>
+
 using namespace std;
 bool isBalanced(string s) {
-	stack<char> st;
-	char ch;
-	for (int i = 0; i < s.length(); i++) {
-		if (s[i] == '(' || s[i] == '[' || s[i] == '{') {
-			st.push(s[i]);
-			continue;
-		}
-		if (st.empty())
-			return false;
-		switch (s[i]) {
-		case ')':
-			ch = st.top();
-			st.pop();
-			if (ch == '{' || ch == '[')
-				return false;
-			break;
-		case '}':
-			ch = st.top();
-			st.pop();
-			if (ch == '(' || ch == '[')
-				return false;
-			break;
-		case ']':
-			ch = st.top();
-			st.pop();
-			if (ch == '(' || ch == '{')
-				return false;
-			break;
-		}
-	}
-	return (st.empty());
+  stack < char > st;
+  char data;
+  int i;
+  /*
+      Logic
+      1. Create a stack of char data type,i of int type and data of char type
+      2. Run a loop till i is less than size
+      3. Assign x[i]th index value in data
+      4. If stack is not empty as well st.top()+2 ==(int) data (we will assume that st.top '[' or '}' so by adding two in it should
+         be ']' pr '}' ) or st.top+1 (we will assume that st.top be '(' so +1 would be ')')
+      5. If the 4 step didn't run then push data in it
+      6. Run the step 4 and 5 till the i is less than x size
+      7. If stack is empty that means the expression is balanced so return 1
+      8. If the 7 step didn't run then return 0 means the expression is not balanced
+      */
+  for (i = 0; i < s.size(); i++) {
+    data = s[i];
+    if ((st.empty() != 1) && ((int)(st.top() + 2) == (int) data || (int)(st.top() + 1) == (int) data))
+      st.pop();
+    else
+      st.push(data);
+  }
+  return (st.empty());
 }
 int main() {
-	string input = "{}[({})]";
-	if (isBalanced(input))
-		cout << "Balanced";
-	else
-		cout << "Not Balanced";
-	return 0;
+  int t;
+  string a;
+  cout << "Enter the number of test cases ";
+  cin >> t;
+  // run loop till t is not equal to 0
+  while (t--) {
+    cout << "Enter the expression ";
+    cin >> a;
+    if (isBalanced(a))
+      cout << "Expression " << a << " is balanced" << endl;
+    else
+      cout << "Expression " << a << " is not balanced" << endl;
+  }
 }
+/*
+Input: Enter the number of test cases: 1
+Enter the expression: ([{}])
+Output:
+Expression ([{}]) is balanced
+
+Time Complexity: O(| x |);
+Space Complexity: O(| x |);
+*/