剑指offer--替换空格

public class Solution {
    public int Find(int start , char c,StringBuffer str){
        int index = -1;
        char[] ch = str.toString().toCharArray();
        for ( int i = start ; i < str.length() ; i++){
            if ( ch[i] == c){
                index = i;
                break;
            }
        }
        return index;
    }

    public String replaceSpace(StringBuffer str) {
        String s = "%20";
        for ( int i = 0 ; i < str.length() ; ){
            int index = Find(i, ' ', str);
            if ( index != -1){
                str.replace(index, index+1,s);
                i = i + 3;
                continue;
            }else{
                i++;
                continue;
            }
        }
        return str.toString();
    }
}

class Solution {
public:
    void replaceSpace(char *str,int length) {
        int oldlength = 0;
        int newlength = 0;
        int i = 0;
        //首先遍历数组计算新数组长度 
        while(str[i] != '\0'){
            oldlength++; 
            if(str[i] == ' '){
                newlength += 3;
            }else{
                newlength++;
            }
            i++;
        }
        //开始替换
        while(oldlength >= 0){
            if(str[oldlength] == ' '){
                str[newlength--] = '0';
                str[newlength--] = '2';
                str[newlength--] = '%';
            }else{
                str[newlength--] = str[oldlength];
            }
            oldlength--;
        } 
    } 
};