1隆豹，題目：給定一個(gè)有符號(hào)的整數(shù)酷麦，將此有符號(hào)整數(shù)反轉(zhuǎn)輸出

-(NSInteger)reverseInt:(NSInteger)ParInt
{
    NSInteger result = 0;
    while (ParInt != 0)
    {
        NSInteger temp = ParInt % 10; //求模運(yùn)算
        ParInt /= 10; //去除最后一位
        result =result * 10 + temp;
    }
    return result;
}

2，判斷一個(gè)整數(shù)是否是回文數(shù)⌒拷觯回文數(shù)是指正序（從左向右）和倒序（從右向左）讀都是一樣的整數(shù)

-(BOOL)isPalindrome:(NSInteger)paraInt
{
    //小于10不是回文數(shù)
    if (paraInt <= 10)
    {
        return NO;
    }
//我們拿反轉(zhuǎn)數(shù)求模剩余的數(shù)字進(jìn)行比較，反轉(zhuǎn)一半的數(shù)就可以崇决，如果是奇數(shù)的話缭裆，我們只需要把他去除掉即可
    NSInteger temp = 0;
    while (temp * 10 < paraInt)
    {
        temp = paraInt % 10 + temp * 10;
        paraInt /= 10;
    }
    return temp == paraInt || temp/10 == paraInt;
}

3，冒泡排序優(yōu)化（ j < sortArray.count - 1 - i 減少循環(huán)次數(shù) bFlag 不需要交換的話可以不用循環(huán)渤昌，加入判空操作）

//我們應(yīng)該在函數(shù)的開(kāi)始去判斷數(shù)組的狀態(tài)已經(jīng)長(zhǎng)度
-(NSArray*)bubbleSort:(NSArray*)array
{
    //判斷數(shù)組狀態(tài)
    if (!array || array.count == 1)
    {
        return array;
    }
    NSMutableArray *sortArray = [NSMutableArray arrayWithArray:array];
    NSInteger execCount = 0;//交換次數(shù)
    BOOL bFlag = YES;//是否已經(jīng)是排序完成
    NSInteger forCount = 0;//for循環(huán)總共執(zhí)行了多少次
    for (NSInteger i = 0; i < sortArray.count && bFlag; i++)
    {
        bFlag = NO;
        forCount++;
        
        for (NSInteger j = 0; j < sortArray.count - 1 - i; j++)
        {
            forCount++;
            if ([sortArray[j] integerValue] > [sortArray[j + 1] integerValue])
            {
                [sortArray exchangeObjectAtIndex:j withObjectAtIndex:j + 1];
                execCount++;
                bFlag = YES;
                [self displayArray:sortArray];
            }
        }
    }
    NSLog(@"交換共執(zhí)行了%ld次", execCount);
    NSLog(@"for循環(huán)共執(zhí)行了%ld次", forCount);
    return sortArray;
}

4虽抄，選擇排序

//選擇排序
//每次把最大的選出來(lái) 放到前面，然后依次類(lèi)推
-(NSArray*)selectSort:(NSArray*)array
{
    if (!array || array.count == 1)
    {
        return array;
    }    
    NSMutableArray *sortResult = [NSMutableArray arrayWithArray:array];
    NSInteger flag;
    NSInteger execCount = 0;//交換次數(shù)
    NSInteger forCount = 0;//for循環(huán)總共執(zhí)行了多少次
    for (NSInteger i = 0; i < sortResult.count; i++)
    {
        flag = i;
        forCount++;
        for (NSInteger j = i; j < sortResult.count - 1; j++)
        {
            if (sortResult[j + 1] > sortResult[flag])
            {
                flag = j + 1;
            }
            forCount++;
        }
        if (i != flag)
        {
            [sortResult exchangeObjectAtIndex:i withObjectAtIndex:flag];
            execCount++;
            [self displayArray:sortResult];
        }
    }
    NSLog(@"交換共執(zhí)行了%ld次", execCount);
    NSLog(@"for循環(huán)共執(zhí)行了%ld次", forCount);
    return sortResult;
}
-(void)displayArray:(NSArray*)array
{
    NSMutableString *displayString = [NSMutableString stringWithString:@"["];
    for (NSInteger i = 0; i < array.count; i++)
    {
        i == array.count - 1 ? [displayString appendString:[NSString stringWithFormat:@"%ld", (long)[array[i] integerValue]]] :[displayString appendString:[NSString stringWithFormat:@"%ld%@", (long)[array[i] integerValue], @","]];
    }
    [displayString appendString:@"]"];
    NSLog(@"%@", displayString);
}

5独柑，羅馬數(shù)字轉(zhuǎn)整數(shù)

-(NSInteger)romanToInt:(NSString*)roman
{
    if([roman integerValue] > 3999 || [roman integerValue] < 1)
    {
        return 0;
    }
    NSInteger result = 0;
    NSInteger romanLen = roman.length;
    NSInteger start = 0;
    if (romanLen == 1)
    {
        result = [self singleRoman:roman];
    }
    else
    {
        while (start < romanLen)
        {
            NSString *temp = [roman substringWithRange:NSMakeRange(start, 1)];
            if ([temp isEqualToString:@"I"] || [temp isEqualToString:@"X"] || [temp isEqualToString:@"C"])
            {
                if (romanLen - start >= 2)
                {
                    NSString *str = [roman substringWithRange:NSMakeRange(start, 2)];
                    if ([str isEqualToString:@"IV"] || [str isEqualToString:@"IX"] || [str isEqualToString:@"XL"] || [str isEqualToString:@"XC"] || [str isEqualToString:@"CD"] || [str isEqualToString:@"CM"] )
                    {
                        result += [self singleRoman:str];
                        start += 2;
                    }
                    else
                    {
                        result += [self singleRoman:temp];
                        start += 1;
                    }
                }
                else
                {
                    result += [self singleRoman:temp];
                    start += 1;
                }
            }
            else
            {
                result += [self singleRoman:temp];
                start += 1;
            }
        }
    }
    NSLog(@"返回的數(shù)字為%ld", result);
    return result;
}
-(NSInteger)singleRoman:(NSString*)roman
{
    if ([roman isEqualToString:@"I"])
    {
        return 1;
    }
    else if ([roman isEqualToString:@"V"])
    {
        return 5;
    }
    else if ([roman isEqualToString:@"X"])
    {
        return 10;
    }
    else if ([roman isEqualToString:@"L"])
    {
        return 50;
    }
    else if ([roman isEqualToString:@"C"])
    {
        return 100;
    }
    else if ([roman isEqualToString:@"D"])
    {
        return 500;
    }
    else if ([roman isEqualToString:@"M"])
    {
        return 1000;
    }
    else if ([roman isEqualToString:@"IV"])
    {
        return 4;
    }
    else if ([roman isEqualToString:@"IX"])
    {
        return 9;
    }
    else if ([roman isEqualToString:@"XL"])
    {
        return 40;
    }
    else if ([roman isEqualToString:@"XC"])
    {
        return 90;
    }
    else if ([roman isEqualToString:@"CD"])
    {
        return 400;
    }
    else if ([roman isEqualToString:@"CM"])
    {
        return 900;
    }
    return 0;
}

6极颓，編寫(xiě)一個(gè)函數(shù)來(lái)查找字符串?dāng)?shù)組中的最長(zhǎng)公共前綴

-(NSString*)longestCommonPrefix:(NSArray*)stringArray
{
    if (stringArray.count == 0)
    {
        return @"";
    }
    else if (stringArray.count == 1)
    {
        return stringArray[0];
    }
    NSString *minString = stringArray[0];
    
    for (NSInteger i = 1; i < stringArray.count; i++)
    {
        NSString *temp = stringArray[i];
        if (temp.length < minString.length)
        {
            minString = temp;
        }
    }
    NSInteger minLen = minString.length;
    minString = stringArray[0];
    NSString *temp;
    NSInteger common = 1;//用來(lái)記錄是否所有的字符串都用相同的前綴
    while (minLen > 0)
    {
        common = 1;//重置
        minString = [minString substringWithRange:NSMakeRange(0, minLen)];
        for (NSInteger i = 1; i < stringArray.count; i++)
        {
            temp = [stringArray[i] substringWithRange:NSMakeRange(0, minLen)];
            if (![minString isEqualToString:temp])
            {
                break;
            }
            else
            {
                common++;
            }
        }
        if (common == stringArray.count)//判斷累計(jì)的次數(shù)是否和數(shù)組長(zhǎng)度相同，如果相同就是為公共前綴
        {
            return minString;
        }
        minLen--;
    }
    return @"";
}

7群嗤，大數(shù)相加

+ (NSString*)additionOfString:(NSString*)strOne AndString:(NSString*)strTwo {

    NSMutableString *One = [NSMutableString stringWithFormat:@"%@",strOne];
    NSMutableString *Two = [NSMutableString stringWithFormat:@"%@",strTwo];
    NSInteger longerLength = 0;
    NSInteger t = 0;
    int jin = 0;
    NSMutableString *strJ = [NSMutableString new];
    NSMutableString *sum = [NSMutableString new];
// 補(bǔ)位：位數(shù)少的用0補(bǔ)齊菠隆，使兩個(gè)字符串位數(shù)相等
    if(One.length > Two.length) {
        t = One.length - Two.length;
        for(NSInteger i =0;i < t;i++) {
           [Two insertString:[NSString stringWithFormat:@"0"] atIndex:0];  
        }
    }else if(One.length < Two.length) {
        NSInteger t = Two.length - One.length;
        for(NSInteger i =0;i < t;i++) {
           [One insertString:[NSString stringWithFormat:@"0"] atIndex:0];
        }
    } else if (One.length== Two.length){
    } else {
        return @"您的輸入有誤！";
    }
    longerLength = One.length;
    for(NSInteger i = longerLength - 1; i >= 0;i--) {
        unichar onenum = [One characterAtIndex:i];
        unichar twonum = [Two characterAtIndex:i];
        int onum = [[NSString stringWithFormat:@"%c",onenum] intValue];
        int tnum = [[NSString stringWithFormat:@"%c",twonum] intValue];
        int c = onum + tnum + jin;
        int z = c%10;
        jin = c/10;
        [strJ appendFormat:@"%d",z];
        if(jin!=0&&i ==0) {
                [strJ appendFormat:@"%d",jin];
          }
    
    }
    // 上面得到的是一個(gè)倒序字符串，需要變成正序
    for(NSInteger i = strJ.length-1; i>= 0;i--) {
        unichar k = [strJ characterAtIndex:i];
        [sum appendFormat:@"%c",k];
    }
    return sum;
}

8骇径，大數(shù)相乘

+ (NSString*)mutiplyOfString:(NSString*)strOne AndString:(NSString*)strTwo {

    NSMutableString *One = [NSMutableString stringWithFormat:@"%@",strOne];
    NSMutableString *Two = [NSMutableString stringWithFormat:@"%@",strTwo];
    int jin = 0;
    NSMutableString *strJ = [NSMutableString new];
    NSMutableString *strT = [NSMutableString new];  // strJ的正序
    NSString *sum = [NSString new];
    NSMutableArray * strJArr = [NSMutableArray array];
    for(NSInteger i = One.length-1; i >=0; i--) {
        strJ = [NSMutableString new];
        strT = [NSMutableString new];
        jin = 0;
        unichar onenum = [One characterAtIndex:i];
        for(NSInteger j = Two.length-1; j >=0; j--){
            unichar twonum = [Two characterAtIndex:j];
            int onum = [[NSString stringWithFormat:@"%c",onenum] intValue];
            int tnum = [[NSString stringWithFormat:@"%c",twonum] intValue];
            int c = onum * tnum +jin;
            int z = c%10;
            jin = c/10;
            if(j != 0) {
                [strJ appendFormat:@"%d",z];
            }else{
                //是否最后一位
                [strJ appendFormat:@"%d",c%10];
                if(c/10 != 0) {
                    [strJ appendFormat:@"%d",c/10];
                }
            }
        }

        // 正序操作
        for(NSInteger a = strJ.length-1; a >= 0;a--) {
            unichar c = [strJ characterAtIndex:a];
            [strT appendFormat:@"%c",c];
        }
        // 將strT放入數(shù)組躯肌，稍后加0后進(jìn)行大數(shù)相加;
        [strJArr addObject:strT];
    }
    if(strJArr.count==0){
        return @"您的輸入有誤！";
    }
    for(NSInteger k =0; k < strJArr.count; k++){
        NSMutableString*strP = strJArr[k];
        // 高位數(shù)補(bǔ)0
        for(NSInteger i = k;i >0;i--) {
            [strP insertString:[NSString stringWithFormat:@"0"] atIndex:strP.length];
        }
        // 大數(shù)相加
        sum = [BigNumberAdd additionOfString:sum AndString:strP];
    }
    return sum;
}