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KiligWY's solution

to Bracket Push in the Objective-C Track

Published at Jul 13 2018 · 0 comments
Instructions
Test suite
Solution

Given a string containing brackets [], braces {} and parentheses (), verify that all the pairs are matched and nested correctly.

Setup

There are two different methods of getting set up to run the tests with Objective-C:

  • Create an Xcode project with a test target which will run the tests.
  • Use the ruby gem objc as a test runner utility.

Both are described in more detail here: http://exercism.io/languages/objective-c

Submitting Exercises

When submitting an exercise, make sure your solution file is in the same directory as the test code.

The submit command will look something like:

exercism submit <path-to-exercism-workspace>/objective-c/bracket-push/BracketPush.m

You can find the Exercism workspace by running exercism debug and looking for the line beginning with Workspace.

Source

Ginna Baker

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

BracketPushTest.m

#import <XCTest/XCTest.h>
#if __has_include("BracketPushExample.h")
# import "BracketPushExample.h"
# else
# import "BracketPush.h"
#endif
@interface BracketPushTest : XCTestCase

@end

@implementation BracketPushTest

- (void)testPairedSquareBrackets {
    XCTAssertTrue([BracketPushExample validateBracketPairingAndNestingInString:@"[]"]);
}

- (void)testEmptyString {
    XCTAssertTrue([BracketPushExample validateBracketPairingAndNestingInString:@""]);
}

- (void)testUnpairedBrackets {
    XCTAssertFalse([BracketPushExample validateBracketPairingAndNestingInString:@"[["]);
}

- (void)testWrongOrderedBrackets {
    XCTAssertFalse([BracketPushExample validateBracketPairingAndNestingInString:@"}{"]);
}

- (void)testPairedWithWhitespace {
    XCTAssertTrue([BracketPushExample validateBracketPairingAndNestingInString:@"{ }"]);
}

- (void)testSimpleNestedBrackets {
    XCTAssertTrue([BracketPushExample validateBracketPairingAndNestingInString:@"{[]}"]);
}

- (void)testSeveralPairedBrackets {
    XCTAssertTrue([BracketPushExample validateBracketPairingAndNestingInString:@"{}[]"]);
}

- (void)testPairedAndNestedBrackets {
    XCTAssertTrue([BracketPushExample validateBracketPairingAndNestingInString:@"([{}({}[])])"]);
}

- (void)testUnopenedClosingBrackets {
    XCTAssertFalse([BracketPushExample validateBracketPairingAndNestingInString:@"{[)][]}"]);
}

- (void)testUnpairedAndNestedBrackets {
    XCTAssertFalse([BracketPushExample validateBracketPairingAndNestingInString:@"([{])"]);
}

- (void)testPairedAndWrongNestedBrackets {
    XCTAssertFalse([BracketPushExample validateBracketPairingAndNestingInString:@"[({]})"]);
}

- (void)testMathExpression {
    XCTAssertTrue([BracketPushExample validateBracketPairingAndNestingInString:@"(((185 + 223.85) * 15) - 543)/2"]);
}

- (void)testComplexLatexExpression {
    XCTAssertTrue([BracketPushExample validateBracketPairingAndNestingInString:@"\\left(\\begin{array}{cc} \\frac{1}{3} & x\\\\ \\mathrm{e}^{x} &... x^2 \\end{array}\\right)"]);
}
@end

BracketPushExample.h

#import <Foundation/Foundation.h>

@interface BracketPushExample : NSObject

+ (BOOL)validateBracketPairingAndNestingInString:(NSString *)string;

@end

BracketPushExample.m

#import "BracketPushExample.h"

@implementation BracketPushExample

+ (BOOL)validateBracketPairingAndNestingInString:(NSString *)string {
    __block NSMutableArray *array = [NSMutableArray array];
    __block BOOL result = YES;
    [string enumerateSubstringsInRange:NSMakeRange(0, string.length) options:NSStringEnumerationByComposedCharacterSequences usingBlock:^(NSString * _Nullable substring, NSRange substringRange, NSRange enclosingRange, BOOL * _Nonnull stop) {
        if ([substring isEqualToString:@"["]
            || [substring isEqualToString:@"{"]
            || [substring isEqualToString:@"("]) {
            [array addObject:substring];
        }
        if ([substring isEqualToString:@"]"]
            || [substring isEqualToString:@"}"]
            || [substring isEqualToString:@")"]) {
            if (([substring isEqualToString:@"]"] && [[array lastObject] isEqualToString:@"["])
                || ([substring isEqualToString:@"}"] && [[array lastObject] isEqualToString:@"{"])
                || ([substring isEqualToString:@")"] && [[array lastObject] isEqualToString:@"("])) {
                [array removeLastObject];
            } else {
                result = NO;
                *stop = YES;
            }
        }
    }];
    return result && (array.count == 0);
}

@end

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