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Mistake in test case Question #230

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Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
45/100
Issue type
Documentation
Clarity
Mostly clear
Activity status
Stale
Tech stack
typescript
Domain
content

Research direction

Open question 230 from the linked DevFAQ page and compare the stated valid test case with the issue’s bracket analysis and TypeScript reproduction. Update the question so the example with the unmatched closing bracket is represented correctly, then verify that the displayed test cases and expected results are consistent.

Written by the indexing model from the issue text.

Description

There is a mistake in this question.

image

It is written that "{dklf(df(kl))d]{}" is a valid test case while it is not due to the not opened "[".

Please update the question.

The code I used to test the cases:

const sum = (arr: number[]): number => arr.reduce((acc, el) => acc+el, 0);

type OpeningBracket = "(" | "[" | "{";
type BracketStackMap = Record<OpeningBracket, number>;

const checkBrackets = (str: string) => {
  const brackets = ["(",")", "[","]", "{","}"]; // "()[]{}".split("");
  
  const filtered = str.split("").filter(character => brackets.includes(character));
  const bracketsStack = new Map<BracketStackMap>([["(", 0], ["[", 0], ["{", 0]]);

  for(let i=0; i<filtered.length; i++){
    // could be simplified with closed/opening bracket key/value mapping
    const key = filtered[i] === ")" ? "("
          : filtered[i] === "]" ? "["
          : filtered[i] === "}" ? "{"
          : filtered[i];
    
    const currentVal = bracketsStack.get(key);
    
    // console.log({i, str: filtered[i], key})
    
    switch(filtered[i]){
      case "(":
      case "[":
      case "{":
        bracketsStack.set(filtered[i], currentVal + 1);
        break;
      case ")":
      case "]":
      case "}":
        bracketsStack.set(key, currentVal - 1);
        break;
      default: throw new Error(`Unhandled bracket: ${filtered[i]}`);
    }
    
    if(bracketsStack.get(key) < 0){
      // console.log("negative", bracketsStack.get(key))
      return false;
    };
  }
  
  return (sum([...bracketsStack.values()]) === 0);
};

const tests = {
  "{ac[bb]}": true, 
  "{dklf(df(kl))d]{}": true, //fails, should pass according to task description
  "{[[[]]]}": true,
  "{3234[fd": false,
  "{df][d}": false
};

Object.entries(tests).forEach(([test, expected]) => {
  const result = (checkBrackets(test) === expected) ? "✅" : "❌";
  
  console.log(`${result} "${test}" `);
});

// results
"✅ '{ac[bb]}' "
"❌ '{dklf(df(kl))d]{}' "
"✅ '{[[[]]]}' "
"✅ '{3234[fd' "
"✅ '{df][d}' "
Dominant language
TypeScript
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