Question

我试着得到这样的输出：

A
BA
ABA
BABA
ABA
BA
A

但我得到了这个：

AB
ABA
ABAB
ABABA
ABABAB

这就是我尝试过的，而且我完全没想到了。

NSString *strA = @"A";
NSString *strB = @"B";

// Capacity does not limit the length, it's just an initial capacity
NSMutableString *result = [NSMutableString stringWithCapacity:[strA length] * 10];

for (int i = 0; i <= 4; i++)
{
    [result appendString:strA];
    [result appendString:strB];
    NSLog(@"%@", result);
}

Answer 1

以下是代码：

NSString *strA = @"A";
NSString *strB = @"B";
int maxLength = 4;

NSMutableString *result = [NSMutableString string];
NSString *stringToAdd = nil;
for (int i = 0; i < maxLength * 2; i++) {
    if (i < maxLength) {
        stringToAdd = [stringToAdd isEqualToString:strA] ? strB : strA;
        [result insertString:stringToAdd atIndex:0];
    } else {
        [result deleteCharactersInRange:NSMakeRange(0, 1)];
    }

    NSLog(@"%@", result);
}

结果：

A  
BA  
ABA  
BABA  
ABA   
BA  
A

我试图显示以下输出

1 个答案: