balance parenthesis: check given string is balanced or not having par…

…enthesis

CodingBlocks Training/Day17/balancedString_paranthesis.java

@@ -0,0 +1,101 @@
+package Lecture17;
+
+import java.util.Stack;
+
+public class balancedString_paranthesis {
+
+	public static void main(String[] args) {
+
+		String str = "{([a+b]+[c+d])}";
+
+		System.out.println(isBalanced(str));
+
+		System.out.println(isBalanced("")); // case 0
+		System.out.println(isBalanced("[a+b"));
+		System.out.println(isBalanced("a+b)])")); // case 2.1
+		System.out.println(isBalanced("a+b+c+d*e-e")); // case 3
+		System.out.println(isBalanced("{[a+b]}"));
+	}
+
+	public static boolean isBalanced(String str) {
+
+		// case 0
+		if (str.equals("")) {
+			return false;
+		}
+		Stack<Character> stack = new Stack<Character>();
+
+		int notParanthesiscount = 0;
+
+		for (int index = 0; index < str.length(); index++) {
+
+			char cc = str.charAt(index);
+
+			// case 1
+			if (cc == '{' || cc == '[' || cc == '(') {
+				stack.push(cc);
+			}
+
+			// case 2
+			else if (cc == '}' || cc == ']' || cc == ')') {
+
+				// case 2.1
+				if (stack.isEmpty()) {
+					return false;
+				}
+
+				char top = stack.peek();
+
+				// case 2.2
+				if (cc == ']') {
+					if (top == '[') {
+						return true;
+					} else {
+						return false;
+					}
+
+					// case 2.3
+				} else if (cc == '}') {
+					if (top == '{') {
+						return true;
+					} else {
+						return false;
+					}
+				}
+
+				// case 2.4
+				else if (cc == ')') {
+					if (top == '(') {
+						return true;
+					} else {
+						return false;
+					}
+				}
+
+			}
+
+			// case 3
+			else {
+				// do nothing for any other character in string rather than
+				// parenthesis
+				notParanthesiscount++;
+			}
+		}
+		if (stack.isEmpty() && notParanthesiscount != str.length()) {
+			return true;
+		} else {
+			return false;
+		}
+	}
+
+}
+
+
+/* output
+true
+false
+false
+false
+false
+true
+*/