剑指offer

Problem

请实现一个函数,将一个字符串中的每个空格替换成“%20”。例如,当字符串为We Are Happy.则经过替换之后的字符串为We%20Are%20Happy。

Solution

正序遍历查找空格,逆序替换,这样这一减少移动元素的操作

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class 
{
public:
void replaceSpace(char *str, int length)
{
if (str == NULL || length <= 0)
{
return;
}

int space = 0;

for (int i = 0; i < length; ++i)
{
if (str[i] == ' ')
{
++space;
}
}

for (int i = length - 1; i >= 0; --i)
{
if (str[i] != ' ')
{
str[i + 2 * space] = str[i];
}
else
{
str[i + 2 * space] = '%';
str[i + 2 * space + 1] = '2';
str[i + 2 * space + 2] = '0';
}
}

return;
}

}