南京三星面试准备1--字符串

字符串

1、把一串字符串里的数字找出来加起来

long long int AddNumInChar(const char* str)
{
	assert(str!=NULL);
	int length=strlen(str);
	long long int result=0;
	for(int i=0;i<length;i++)
	{
		if(str[i]>='0'&&str[i]<='9')
		{
			result+=str[i]-'0';
		}
	}
	return result;
}

2、把字符串转换成整数

void Char2Int(const char*str)
{
	assert(str!=NULL);
	int length=strlen(str);
	long long int result=0;
	bool flag=false;
	bool fuhao=true;

	for(int i=0;i<length;i++)
	{
		if(i==0&&(str[0]=='+'||str[0]=='-'))
		{
			fuhao=str[0]=='-'?false:true;	
		}
		else if(str[i]>='0'&&str[i]<='9')
		{
			flag=true;
			result=result*10+str[i]-'0';
		}
		else
		{
			printf("My God
"); 
			return;
		}

	}
	if(!fuhao)
		result=result*(-1);
	printf("%lld
",result);

}

3、把字符串顺序倒过来

char* reverseString(char* str)
{
	assert(str!=NULL);
	int length=strlen(str);
	for(int i=0;i<length/2;i++)
	{
		char temp=str[i];
		str[i]=str[length-i-1];
		str[length-i-1]=temp;
	}
	return str;
}

4、找字符串里的回数

char *FindString(const char *str)
{
	assert(str!=NULL);
	int length=strlen(str);
	int *numbers=new int[length];
	float *index=new float[length];
	numbers[0]=numbers[length-1]=1;
	index[0]=0;
	index[length-1]=length-1;
	int left,right;
	for(int i=1;i<length-1;i++)
	{
		left=i-1;
		right=i+1;
		if(str[left]!=str[right]&&str[left]!=str[i]&&str[i]!=str[right])
		{
			numbers[i]=1;
			index[i]=i;
		}
		else 
		{
			if(str[left]==str[right])
			{
				numbers[i]=3;
				index[i]=i;
			}
			else if(str[left]==str[i])
			{
				numbers[i]=2;
				index[i]=(left+i)/2.0;
				right=i;
			}
			else if(str[i]==str[right])
			{
				numbers[i]=2;
				index[i]=(right+i)/2.0;
				left=i;
			}
			while(--left>=0&&++right<length)
			{
				if(str[left]==str[right])
					numbers[i]+=2;
				else
					break;
			}
		}
	}
	int max=numbers[0];
	int tempI=0;
	for(int i=0;i<length;i++)
	{
		if(numbers[i]>max)
		{
			tempI=i;
			max=numbers[i];
		}
	}
	char *result=new char[max];
	for(int i=0;i<max;i++)
	{
		int temp=floor(i+index[tempI]-max/2+0.5);
		result[i]=str[temp];
	}
	delete []numbers;
	return result;
}

5、替换空格为%20：

char* ChangeString(char* myChar,int length)
{
    char* result=new char[length*3];
 
    int count=0;
    for(int i=0;i<length;i++)
    {
        if(myChar[i]==' ')
        {
            result[count++]='%';
            result[count++]='2';
            result[count++]='0';
        }
        else
        {
            result[count++]=myChar[i];
        }
    }
    result[count]='';
    return result;
}

6、翻转单词顺序

void Reverse(char* const numbers,int length)
{
	char temp;
	for(int i=0;i<length/2;i++)
	{
		temp=numbers[i];
		numbers[i]=numbers[length-i-1];
		numbers[length-i-1]=temp;
	}
}

void PrintReverse(char* const numbers,int length)
{
	int i=0;
	Reverse( numbers,length);
	int letterLen=0,begin=0;i=0;
	bool flag=true;
	while(numbers[i]!='')
	{
		if(numbers[i]!=' ')
		{
			flag=true;
			letterLen++;
		}
		else if(flag)
		{
			if(letterLen>1)
				Reverse(numbers+begin,letterLen);
			letterLen=0;
			begin=i+1;
			flag=false;
		}
		else
			begin++;
		i++;
	}
	Reverse(numbers+begin,letterLen);
	printf("%s
",numbers);
}

左旋转字符串
void Reverse(char* const numbers,int length)
{
char temp;
for(int i=0;i<length/2;i++)
{
temp=numbers[i];
numbers[i]=numbers[length-i-1];
numbers[length-i-1]=temp;
}
}
void PrintMov(char* const numbers,int move)
{
int length=strlen(numbers);
move=move%length;


Reverse( numbers,length);


Reverse(numbers,length-move);
Reverse(numbers+length-move,move);
printf("%s ",numbers);
}

7、第一次只出现一次的字符

int FirstOneCharacter(const char* characters)
{
	int appearances[LetterNum]={0};
	int result=-1;
	if(characters==NULL)
		return result;
	int length=strlen(characters);
	
	for(int i=0;i<length;i++)
	{
		appearances[characters[i]-'A']++;
	}
	for(int i=0;i<length;i++)
	{
		if(appearances[characters[i]-'A']==1)
		{
			result=i;
			break;
		}
	}
	return result;
}

8、字符串的全排列：

void Permutation(char* source,char *begin);
void Permutation(char* source)
{
	int length=strlen(source);
	if(source==NULL||length<=0)
		return;
	Permutation(source,source);

}

int *Sort(char *arrays)
{
	int length=strlen(arrays);
	char temp;
	int *index=new int[length];
	int tempIndex;
	for(int i=0;i<length;i++)
	{
		index[i]=i;
	}
	for(int i=0;i<length;i++)
	{
		for(int j=i;j<length;j++)
		{
			if(arrays[j]<arrays[i])
			{
				temp=arrays[j];
				arrays[j]=arrays[i];
				arrays[i]=temp;
				tempIndex=index[j];
				index[j]=index[i];
				index[i]=tempIndex;
			}
		}
	}
	return index;
}

void Permutation(char* source,char *begin)
{
	if(begin[0]=='')
		printf("%s
",source);
	else
	{
		int length=strlen(begin);
		char *temp=new char[length+1];
		int i=0;
		char word;
		int *index;
		temp=strcpy(temp,begin);
		index=Sort(temp);
		
		for(;i<length;i++)
		{
			if(i>0&&temp[i]==temp[i-1])
				continue;
			swap(begin[0],begin[index[i]]);
			Permutation(source,begin+1);
			swap(begin[0],begin[index[i]]);
		}
		delete []temp;
		delete []index;

	}
}