Leetcode 504，How to replace Space with %20

    private static char[] replaceSpaceInString(char[] str, int length) {
        int spaceCounter = 0;

        //First lets calculate number of spaces
        for (int i = 0; i < length; i++) {
            if (str[i] == ' ') {
                spaceCounter++;
            }
        }

        //calculate new size
        int newLength = length + 2 * spaceCounter;

        char[] newArray = new char[newLength + 1];
        newArray[newLength] = '\0';

        int newArrayPosition = 0;

        for (int i = 0; i < length; i++) {
            if (str[i] == ' ') {
                newArray[newArrayPosition] = '%';
                newArray[newArrayPosition + 1] = '2';
                newArray[newArrayPosition + 2] = '0';
                newArrayPosition = newArrayPosition + 3;
            } else {
                newArray[newArrayPosition] = str[i];
                newArrayPosition++;
            }
        }
        return newArray;
    }

refer:  http://stackoverflow.com/questions/10007631/write-a-method-to-replace-all-spaces-in-a-string-with-20