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Description html markup shown to student	​ You're working with an intern that keeps coming to you with C++ code that won't run because the <tt>{</tt>braces<tt>}</tt>, <tt>(</tt>brackets<tt>)</tt>, and <tt>(</tt>parentheses<tt>)</tt> are off. To save you both some time, you decide to write a braces/brackets/parentheses validator. ​ <p> Write a function <tt>bracket_check</tt> that takes a <tt>string</tt> and returns <tt>true</tt> if the braces/brackets/parentheses are matched, and <tt>false</tt> otherwise. You can assume all other characters have been deleted: the string can only contain some mix of <tt>()[]{}</tt> characters (possibly multiple times). ​ <p>E.g.: <tt>"{[]()}"</tt> and <tt>"[(())]"</tt> should return <tt>true</tt>, and <tt>")("</tt> and <tt>"(]"</tt> should return <tt>false</tt>. ​ <p>You may assume that the string has length at most 100. ​
Epilogue html markup shown when solved	​ remove
Public permissions	open: anyone can solve, see in listings, see sourceopen: open, but when viewing source, redact solution (default)closed-source, but list publicly and anyone can attempt itclosed-source, and hide from listings (need direct URL to attempt)draft: don't let anyone other than me see this at all remove
Remarks Comments, history, license, etc.	​ based on this Creative Commons Att-SA 3.0 exercise: https://cloudcoder.org/repo/exercise/6cdc568f0b5fac4c019de701dd849f4396d7670b ​ remove
Engine	Select one... (default)JavaC++ (call main with stdin and args)C++ (call functions directly)Multiple true/falseShort answer
Choices json list of string, bool pairs e.g. [["good", true], ["bad", false]]	​
Correct answer
Template / Reference solution	​
Template / Reference solution	​ #include <iostream> #include <cstdlib> using namespace std; ​ bool bracket_check(string expr) { \[ // we'll scan through the string in a single pass // the strategy will be to remember how "deep" we're nested int depth = 0; // and what kinds of brackets contain us, memory[0] being the outermost char memory[100]; ​ for (int i=0; i<expr.length(); i++) { if (expr[i] == '(' || expr[i] == '{' || expr[i] == '[') { // remember entering this depth++; memory[depth-1] = expr[i]; } else if (expr[i] == ')' || expr[i] == '}' || expr[i] == ']') { // closer not matching any previous opener if (depth == 0) return false; // see if closer and opener have same style char should_match = memory[depth-1]; depth--; if (expr[i] == ')' && should_match != '(') return false; if (expr[i] == ']' && should_match != '[') return false; if (expr[i] == '}' && should_match != '{') return false; } } // done scanning the string. we'd better be at level 0... return (depth == 0); ]\ } ​
Java test suite See manual	​
C++ test suite json list of stdin/args tests e.g. [{"stdin":"hi", "args":["4", "5"]}, {"stdin":"noargs"}] to just run once with no input use [{}]	​
C++ test suite See manual	[ ["check-function", "bracket_check", "bool", ["string"]], ["call-function", "bracket_check", ["\"()()\""]], ["call-function", "bracket_check", ["\"(())\""]], ["call-function", "bracket_check", ["\"())(\""]], ["call-function", "bracket_check", ["\"((())\""]], ["call-function", "bracket_check", ["\"([])\""]], ["call-function", "bracket_check", ["\"{}[]\""]], ["call-function", "bracket_check", ["\"{[}]\""]], ["call-function", "bracket_check", ["\"([]{})\""]], ["call-function", "bracket_check", ["\"([()][([[]][]){()}])\""]], ["call-function", "bracket_check", ["\"([()][([[]][]}{()}])\""]], ["call-function", "bracket_check", ["\"([(]][([[]][]){()}])\""]], ["call-function", "bracket_check", ["\"([()][([[]][]){())])\""]], ["call-function", "bracket_check", ["\"([()][([[]][]){()]])\""]], ["call-function", "bracket_check", ["\"([()][([[)][]){()}])\""]], ["call-function", "bracket_check", ["\"([()][([[]}[]){()}])\""]], ["call-function", "bracket_check", ["\"([()][([[]][]){()}]))\""]], ["call-function", "bracket_check", ["\"([()][([[]][]){()}]\""]] ] ​
Forbidden substrings json list of strings e.g. ["for","while"]	​ remove
Solution visibility	AlwaysAfter 1 attemptAfter solving or 2 attemptsAfter solving or 3 attemptsAfter solving or 4 attemptsAfter solving or 5 attemptsAfter solving (default)Never remove
Java imports json list of importables e.g. ["java.util.*"]	​ remove
Override Java classname else defaults to websheet name	remove
Dependent on other websheets? json list of websheet names in this folder e.g. ["DataStructure"]	​ remove
Is example? i.e., just a demo	False (default)True remove
Add compiler flag(s) json list of flags e.g. ["-Wno-unused-variable"]	​ remove
Remove default compiler flag(s) json list of flags see default_cppflags e.g. ["-Wno-write-strings"]	​ remove

Optional properties:

Note: problems are open-source by default (see 'Public permissions'). Assumed license for open problems is Creative Commons 4.0 Attribution-ShareAlike unless specified in 'Remarks'.