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## to Transpose in the Objective-C Track

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

Given an input text output it transposed.

Roughly explained, the transpose of a matrix:

``````ABC
DEF
``````

is given by:

``````AD
BE
CF
``````

Rows become columns and columns become rows. See https://en.wikipedia.org/wiki/Transpose.

If the input has rows of different lengths, this is to be solved as follows:

• Pad to the left with spaces.
• Don't pad to the right.

Therefore, transposing this matrix:

``````ABC
DE
``````

results in:

``````AD
BE
C
``````

And transposing:

``````AB
DEF
``````

results in:

``````AD
BE
F
``````

In general, all characters from the input should also be present in the transposed output. That means that if a column in the input text contains only spaces on its bottom-most row(s), the corresponding output row should contain the spaces in its right-most column(s).

## 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/transpose/Transpose.m
``````

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

## Source

Reddit r/dailyprogrammer challenge #270 [Easy]. https://www.reddit.com/r/dailyprogrammer/comments/4msu2x/challenge_270_easy_transpose_the_input_text

## Submitting Incomplete Solutions

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

### TransposeTest.m

``````#import <XCTest/XCTest.h>

#if __has_include("TransposeExample.h")
# import "TransposeExample.h"
# else
# import "Transpose.h"
#endif

@interface TransposeTest : XCTestCase

@end

@implementation TransposeTest

- (void)testEmptyInput {
XCTAssertEqualObjects([Transpose transpose:@[]], @[]);
}

- (void)testTwoCharactersInARow {
NSArray<NSString *> *input = @[@"A1"];
NSArray<NSString *> *expected = @[@"A", @"1"];
XCTAssertEqualObjects([Transpose transpose:input], expected);
}

- (void)testTwoCharactersInAColumn {
NSArray<NSString *> *input = @[@"A", @"1"];
NSArray<NSString *> *expected = @[@"A1"];
XCTAssertEqualObjects([Transpose transpose:input], expected);
}

- (void)testSimple {
NSArray<NSString *> *input = @[@"ABC", @"123"];
NSArray<NSString *> *expected = @[@"A1", @"B2", @"C3"];
XCTAssertEqualObjects([Transpose transpose:input], expected);
}

- (void)testSingleLine {
NSArray<NSString *> *input = @[@"Single line."];
NSArray<NSString *> *expected = @[@"S", @"i", @"n", @"g", @"l", @"e", @"", @"l", @"i", @"n", @"e", @"."];
XCTAssertEqualObjects([Transpose transpose:input], expected);
}

- (void)testFirstLineLongerThanSecondLine {
NSArray<NSString *> *input = @[@"The fourth line.", @"The fifth line."];
NSArray<NSString *> *expected = @[@"TT", @"hh", @"ee", @"", @"ff", @"oi", @"uf", @"rt", @"th", @"h", @" l", @"li", @"in", @"ne", @"e.", @"."];
XCTAssertEqualObjects([Transpose transpose:input], expected);
}

- (void)testSecondLineLongerThanFirstLine {
NSArray<NSString *> *input = @[@"The first line.", @"The second line."];
NSArray<NSString *> *expected = @[@"TT", @"hh", @"ee", @"", @"fs", @"ie", @"rc", @"so", @"tn", @" d", @"l", @"il", @"ni", @"en", @".e", @" ."];
XCTAssertEqualObjects([Transpose transpose:input], expected);
}

- (void)testSquare {
NSArray<NSString *> *input = @[@"HEART", @"EMBER", @"ABUSE", @"RESIN", @"TREND"];
NSArray<NSString *> *expected = @[@"HEART", @"EMBER", @"ABUSE", @"RESIN", @"TREND"];
XCTAssertEqualObjects([Transpose transpose:input], expected);
}

- (void)testRectangle {
NSArray<NSString *> *input = @[@"FRACTURE", @"OUTLINED", @"BLOOMING", @"SEPTETTE"];
NSArray<NSString *> *expected = @[@"FOBS", @"RULE", @"ATOP", @"CLOT", @"TIME", @"UNIT", @"RENT", @"EDGE"];
XCTAssertEqualObjects([Transpose transpose:input], expected);
}

- (void)testTriangle {
NSArray<NSString *> *input = @[@"T", @"EE", @"AAA", @"SSSS", @"EEEEE", @"RRRRRR"];
NSArray<NSString *> *expected = @[@"TEASER", @" EASER", @"  ASER", @"   SER", @"    ER", @"     R"];
XCTAssertEqualObjects([Transpose transpose:input], expected);
}

- (void)testManyLines { //!OCLINT
NSArray<NSString *> *input = @[@"Chor. Two households, both alike in dignity,",
@"In fair Verona, where we lay our scene,",
@"From ancient grudge break to new mutiny,",
@"Where civil blood makes civil hands unclean.",
@"From forth the fatal loins of these two foes",
@"A pair of star-cross'd lovers take their life;",
@"Whose misadventur'd piteous overthrows",
@"Doth with their death bury their parents' strife.",
@"The fearful passage of their death-mark'd love,",
@"And the continuance of their parents' rage,",
@"Which, but their children's end, naught could remove,",
@"Is now the two hours' traffic of our stage;",
@"The which if you with patient ears attend,",
@"What here shall miss, our toil shall strive to mend."
];

NSArray<NSString *> *expected = @[
@"CIFWFAWDTAWITW",
@"hnrhr hohnhshh",
@"o oeopotedi ea",
@"rfmrmash  cn t",
@".a e ie fthow",
@" ia fr weh,whh",
@"Trnco miae  ie",
@"w ciroitr btcr",
@"oVivtfshfcuhhe",
@" eeih a uote",
@"hrnl sdtln  is",
@"oot ttvh tttfh",
@"un bhaeepihw a",
@"saglernianeoyl",
@"e,ro -trsui ol",
@"h uofcu sarhu",
@"owddarrdan o m",
@"lhg to'egccuwi",
@"deemasdaeehris",
@"sr als t  ists",
@",ebk 'phool'h,",
@"  reldi ffd",
@"bweso tb  rtpo",
@"oea ileutterau",
@"t kcnoorhhnatr",
@"hl isvuyee'fi",
@" atv es iisfet",
@"ayoior trr ino",
@"l  lfsoh  ecti",
@"ion   vedpn  l",
@"kuehtteieadoe",
@"erwaharrar,fas",
@"   nekt te  rh",
@"ismdsehphnnosa",
@"ncuse ra-tau l",
@" et  tormsural",
@"dniuthwea'g t",
@"iennwesnr hsts",
@"g,ycoi tkrttet",
@"n ,l r s'a anr",
@"i  ef  'dgcgdi",
@"t  aol   eoe,v",
@"y  nei sl,u; e",
@",  .sf to l",
@"     e rv d  t",
@"     ; ie    o",
@"       f, r",
@"       e  e  m",
@"       .  m  e",
@"          o  n",
@"          v  d",
@"          e  .",
@"          ,"
];

XCTAssertEqualObjects([Transpose transpose:input], expected);
}

@end``````

### Transpose.h

``````#import <Foundation/Foundation.h>

@interface Transpose : NSObject

+ (NSArray *)transpose:(NSArray *)array;

@end``````

### Transpose.m

``````#import "Transpose.h"

@implementation Transpose

+ (NSArray *)transpose:(NSArray *)array {
NSInteger length = 0;
for (NSString *sunstring in array) {
length = MAX(length, sunstring.length);
}
NSMutableArray *result = [NSMutableArray array];
for (NSInteger i = 0; i < length; ++i) {
NSString *string = @"";
for (NSInteger j = 0; j < array.count; ++j) {
NSString *obj = array[j];
if (obj.length > i) {
string = [string stringByAppendingString:[obj substringWithRange:NSMakeRange(i, 1)]];
} else {
string = [string stringByAppendingString:@" "];
}
}
while ([string hasSuffix:@" "]) {
string = [string substringToIndex:string.length - 1];
}
[result addObject:string];
}
return result;
}

@end``````

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