CareerCup 150

C.C 1.4

/**
 * 1.4 Write a method to replace all spaces in a string with'%20'. You may
 * assume that the string has sufficient space at the end of the string to hold
 * the additional characters, and that you are given the "true" length of the
 * string. (Note: if implementing in Java, please use a character array so that
 * you can perform this operation in place.) EXAMPLE
 *
 * Input: "Mr John Smith "
 *
 * Output: "Mr%20Dohn%20Smith"
 *
 * @author Jiateng
 */
public class CC1_4 {

    //Time O(n), Space O(n)
    public static String replace1(String target) {

        StringBuilder result = new StringBuilder();

        char[] array = target.toCharArray();

        for (int i = 0; i < array.length; i++) {
            if (array[i] != ' ') {
                result.append(array[i]);
            } else {
                result.append("%20");
            }
        }

        return result.toString();
    }

    //Time O(n), Space O(n)
    public static String replace2(String target) {

        char[] array = target.toCharArray();
        int len = array.length;
        int spaceCount = 0;
        int newLen = 0;

        for (int i = 0; i < len; i++) {
            if (array[i] == ' ') {
                spaceCount++;
            }
        }
        //space will be replaced by %20
        newLen = len + spaceCount * 2;
        char[] newArray = new char[newLen];

        for (int i = len - 1; i >= 0; i--) {
            if (array[i] == ' ') {
                newArray[newLen - 1] = '0';
                newArray[newLen - 2] = '2';
                newArray[newLen - 3] = '%';
                newLen -= 3;
            } else {
                newArray[newLen - 1] = array[i];
                newLen -= 1;
            }
        }
        return new String(newArray);
    }

    public static void main(String[] args) {
        System.out.println(replace1(" iisfd sdfs sdfs "));
        System.out.println(replace2(" iisfd sdfs sdfs "));
    }
}