Sword finger offer 05 Replace spaces: replace each space in the string s with "%20"“

solution 1:API Just use it

class Solution {
    
    public String replaceSpace(String s) {
    
         s = s.replace(" ", "%20");
            return s;
    }
}

interviewer ：API It works very well , Go back and wait for the announcement

solution 2:
Algorithm flow ：

• Initialize a list (Python) / StringBuilder (Java) , Write it down as res ;
• Traverse the list s Each character in c ：
  When c When is a space ： towards res Add string after “%20” ;
  When c When not a space ： towards res Add characters after c ;
• Will list res Convert to a string and return .

public class ReplaceBlank05 {
    
    public static void main(String[] args) {
    
        String s = replaceSpace("We are happy.");
        System.out.println(s);
    }


        public static String replaceSpace(String s) {
    
           StringBuilder stringBuilder = new StringBuilder();
            for (int i = 0; i < s.length(); i++) {
    
                if (s.charAt(i) == ' '){
    
                    stringBuilder.append("%20");
                }else{
    
                    stringBuilder.append(s.charAt(i));
                }
            }
            return stringBuilder.toString();
        }
}