86 lines
2.7 KiB
Java
86 lines
2.7 KiB
Java
package data_structures.Stacks;
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import java.util.Scanner;
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import java.util.Stack;
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/**
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*
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* The nested brackets problem is a problem that determines if a sequence of
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* brackets are properly nested. A sequence of brackets s is considered properly
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* nested if any of the following conditions are true: - s is empty - s has the
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* form (U) or [U] or {U} where U is a properly nested string - s has the form
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* VW where V and W are properly nested strings For example, the string
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* "()()[()]" is properly nested but "[(()]" is not. The function called
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* is_balanced takes as input a string S which is a sequence of brackets and
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* returns true if S is nested and false otherwise.
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*
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* @author akshay sharma
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* @date: 2017-10-17
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* @author <a href="https://github.com/khalil2535">khalil2535<a>
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*
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*/
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class BalancedBrackets {
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/**
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*
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* @param s
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* @return
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*/
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static boolean is_balanced(String s) {
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Stack<Character> bracketsStack = new Stack<>();
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char[] text = s.toCharArray();
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for (char x : text) {
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switch (x) {
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case '{':
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case '<':
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case '(':
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case '[':
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bracketsStack.push(x);
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break;
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case '}':
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if (!bracketsStack.empty() && bracketsStack.pop() == '{') {
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break;
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} else {
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return false;
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}
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case '>':
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if (!bracketsStack.empty() && bracketsStack.pop() == '<') {
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break;
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} else {
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return false;
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}
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case ')':
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if (!bracketsStack.empty() && bracketsStack.pop() == '(') {
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break;
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} else {
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return false;
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}
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case ']':
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if (!bracketsStack.empty() && bracketsStack.pop() == '[') {
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break;
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} else {
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return false;
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}
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}
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}
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return bracketsStack.empty();
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}
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/**
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*
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* @param args
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* @TODO remove main method and Test using JUnit or other methodology
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*/
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public static void main(String args[]) {
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try (Scanner in = new Scanner(System.in)) {
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System.out.println("Enter sequence of brackets: ");
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String s = in.nextLine();
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if (is_balanced(s)) {
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System.out.println(s + " is balanced");
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} else {
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System.out.println(s + " ain't balanced");
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}
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}
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}
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}
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