README_EN.md

01.03. String to URL

中文文档

Description

Write a method to replace all spaces in a string with '%20'. You may assume that the string has sufficient space at the end 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 1:

Input: "Mr John Smith ", 13

Output: "Mr%20John%20Smith"

Explanation: 

The missing numbers are [5,6,8,...], hence the third missing number is 8.

Example 2:

Input: "               ", 5

Output: "%20%20%20%20%20"

 

Note:

1. 0 <= S.length <= 500000

Solutions

Python3

class Solution:
    def replaceSpaces(self, S: str, length: int) -> str:
        S = S[:length] if length < len(S) else S
        return S.replace(' ', '%20')

Java

class Solution {
    public String replaceSpaces(String S, int length) {
        char[] c = S.toCharArray();
        int j = c.length;
        for (int i = length - 1; i >= 0; i--) {
            if (c[i] == ' ') {
                c[--j] = '0';
                c[--j] = '2';
                c[--j] = '%';
            } else {
                c[--j] = c[i];
            }
        }
        return new String(c, j, c.length - j);
    }
}

...