剑指Offer---替换空格

class Solution {
public:
void replaceSpace(char *str,int length)
{
int n = 0;
for(int i=0; i<length; i++)
{
if(str[i] == ' ')
n++;
}
int length1 = n*2 + length;
int id1 = length - 1, id2 = length1 - 1;
while(id1 >= 0)
{
if(str[id1] != ' ')
{
str[id2--] = str[id1--];
}
else
{
str[id2--] = '0';
str[id2--] = '2';
str[id2--] = '%';
id1--;
}
}
}
};