剑指offer-问题4

package offer;

/**
 * offer interview 4
 */
public class Test04 {

    public static int replaceBlank(char[] string,int usedLength){

        if (null == string || string.length < usedLength){
            return -1;
        }

        int whiteCount = 0;
        for (int i = 0 ; i < usedLength ; i++){
            if (string[i] == ' '){
                whiteCount++;
            }
        }

        int targetLength = whiteCount * 2 + usedLength;
        int temp = targetLength;
        if (targetLength > string.length){
            return -1;
        }

        if (0 == whiteCount){
            return usedLength;
        }

        usedLength--;
        targetLength--;

        while(usedLength >= 0 && usedLength < targetLength){
            if (string[usedLength] == ' '){
                string[targetLength--] = '0';
                string[targetLength--] = '2';
                string[targetLength--] = '%';
            }else{
                string[targetLength--] = string[usedLength];
            }
            usedLength--;
        }
        return temp;
    }

    public static void main(String[] args){
        char[] string = new char[50];
        string[0] = ' ';
        string[1] = 'e';
        string[2] = ' ';
        string[3] = ' ';
        string[4] = 'r';
        string[5] = 'e';
        string[6] = ' ';
        string[7] = ' ';
        string[8] = 'a';
        string[9] = ' ';
        string[10] = 'p';
        string[11] = ' ';

        int length = replaceBlank(string,12);
        System.out.println(new String (string,0,length));
    }

}