替换空格

class Solution {
public:
    void replaceSpace(char *str, int length) {
        int spaceNum = 0;
        
        for(int i = 0; i < length; ++i) {
            if(str[i] == ‘ ‘)
                ++spaceNum;
        }
        
        int newIndex = length + 2 * spaceNum - 1;
           int index = length - 1;
        while(index >= 0) {
            if(str[index] == ‘ ‘) {
                str[newIndex--] = ‘0‘;
                str[newIndex--] = ‘2‘;
                str[newIndex--] = ‘%‘;
            }
            else 
                str[newIndex--] = str[index];
            
            index--;
        }
    }
};