C++:一点点算法

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/*
* 判断字符串是不是回文字符串
*/
bool IsPalindrone(const char *s,int n)
{
    if(s == NULL || n < 1)
    {
        return false;
    }
    char *first,char *second;
    int m = (n/2-1) > 0?(n/2-1):0;
    first = s + m;//移位
    second = s+n-1-m;
    while (first >= s)
    {
        /* code */
        if(*first-- != *second++)
        {
            return false;
        }
    }
    return true;
}

/*
* 实现旋转部分字符串,比如abcdefg->efgabcd
* 要旋转的两部分先分别旋转,然后整体翻转
*/
void ReversionString(char *s,int from,int to)
{
    while (from < to)
    {
        /* code */
        char temp = s[from];
        s[from++] = s[to];
        s[to--] = temp;
    } 
}

void RotationString(char *s,int len,int m)
{
    m = m % len;
    ReversionString(s,0,m-1);
    ReversionString(s,m,len-1);
    ReversionString(s,0,len-1);
}
/*
  查找字符串中出现次数最多的字符和出现的次数
*/
int main()
{
	const char* ps = "hahhah";
 
    char c = '\0';
    size_t counts[256] = { 0 };
    for( const char* p=ps; *p; ++p )
    {
        ++counts[*p];
        if( counts[*p] > counts[c] )
            c = *p;
    }
 
    printf( "Character=%c, count=%zu\n", c, counts[c] );
    return 0;
}

/*
   去掉句子里面的空格
*/
#include <iostream>

using namespace std;

int main()
{
	char a[40] = "i  have a dream ";
	int i;
	int num = 0;
	for (i = 0; a[i] != '\0'; ++i)
	{
		if (a[i] == ' ')
		{
			++num;
		}
		else
		{
			a[i - num] = a[i];
		}
	}
	a[i - num] = '\0';
	cout << a << endl;
	system("PAUSE");
	return 0;
}
/*
  将空格替换成其他字符
*/
#include <iostream>

using namespace std;

void ReplaceBlank(char string[],int length)
{
	if (string == nullptr && length <= 0)
	{
		return;
	}
	int originalLength = 0;
	int numberOfBlank = 0;
	int i = 0;
	while (string[i] != '\0')
	{
		++originalLength;
		if (string[i] == ' ')
		{
			numberOfBlank++;
		}
		++i;
	}

	int newLength = originalLength + numberOfBlank * 2;
	if (newLength > length)
	{
		return;
	}
	int indexOfOriginal = originalLength;
	int indexOfNew = newLength;
	while (indexOfOriginal >= 0 && indexOfNew > indexOfOriginal)
	{
		if (string[indexOfOriginal] == ' ')
		{
			string[indexOfNew--] = '0';
			string[indexOfNew--] = '2';
			string[indexOfNew--] = '%';
		}
		else
		{
			string[indexOfNew--] = string[indexOfOriginal];
		}

		--indexOfOriginal;
	}
}

int main()
{
	const int length = 100;

	char string[length] = "hello world";

	ReplaceBlank(string, length);
	system("PAUSE");
	return 0;
}