Question

link

String replace, 给一个原 string，一个 target，一个替换的新 str，把所有出现
target str 的地方都换成新的 str， 长度可以任意.

Solution

If the question asks for an in-place algo, then we can refer to Question 1.5 in CC150v4.

Question

1.5 Write a method to replace all spaces in a string with ‘%20’.

Solution

  1. pre-processing, count the number of spaces in string
  2. parse the string from end to beginning.

Need 2 pass.

Code

not written by me

public static void ReplaceFun(char[] str, int length) {
    int spaceCount = 0, newLength, i = 0;
    for (i = 0; i < length; i++) {
        if (str[i] == ' ') {
            spaceCount++;
        }
    }
    newLength = length + spaceCount * 2;
    str[newLength] = '\0';
    for (i = length - 1; i >= 0; i--) {
        if (str[i] == ' ') {
            str[newLength - 1] = '0';
            str[newLength - 2] = '2';
            str[newLength - 3] = '%';
            newLength = newLength - 3;
        } else {
            str[newLength - 1] = str[i];
            newLength = newLength - 1;
        }
    }
}