Sword refers to Java Implementation of offer programming questions -- interview question 4 replaces spaces, and sword refers to offer

Sword refers to Java Implementation of offer programming questions -- interview question 4 replaces spaces, and sword refers to offer
Implement a function to replace spaces in a string with "% 20 ". For example, if the string is We Are Happy, the replaced string is We % 20Are % 20 Happy.

1 package Solution; 2 3/** 4 * offoffoffer interview question 4: replace space 5 * Question: Please use a function to replace each space in the string with "% 20 ". 6 * For example, if "We are happy." Is input, "We % 20are % 20happy." Is output .". 7 * @ author GL 8*9 */10 public class No4ReplaceSpace {11 12 public static void main (String [] args) {13 String string1 = "We are happy. "; 14 String string2 =" We are happy. "; 15 String string3 =" Wearehappy. "; 16 // String string4 = null; 17 String string5 =" "; 18 String string6 =" "; 19 String string7 =" "; 20 System. out. println (replaceSpace (string1.toCharArray (); 21 System. out. println (replaceSpace (string2.toCh ArArray (); 22 System. out. println (replaceSpace (string3.toCharArray (); 23 // System. out. println (replace (string4.toCharArray (); 24 System. out. println (replaceSpace (string5.toCharArray (); 25 System. out. println (replaceSpace (string6.toCharArray (); 26 System. out. println (replaceSpace (string7.toCharArray (); 27 System. out. println (replaceSpace (new StringBuffer (string1); 28 System. out. println (replaceSpac E (new StringBuffer (string2); 29 System. out. println (replaceSpace (new StringBuffer (string3); 30 // System. out. println (replaceSpace (new StringBuffer (string4); 31 System. out. println (replaceSpace (new StringBuffer (string5); 32 System. out. println (replaceSpace (new StringBuffer (string6); 33 System. out. println (replaceSpace (new StringBuffer (string7); 34} 35 36/* 37 * time complexity is O (n) solution: use the array to replace 38*1 from the back and forward. traverse the array once. String to calculate the number of characters to replace 39*2. Create a temporary array, the array length is the number of characters in the initial string + the number of characters to replace each character * The number of characters to replace is 40*3. The original string array is copied forward and replaced with the temporary array.. The two array subscript variables are respectively the length of the original character array-1, the length of the temporary array-141*4, if the character of the original character array is not a space, copy this character to the corresponding position of the temporary array. Both arrays are marked with a minus of 142*5. If the character of the original character array is a space, then, replace the character corresponding to the temporary array from the back to the front, reduce the number of replacement characters in the temporary array subscript by 43*6, and replace by cyclic replication, after the subscript of the initial array is less than 0, the replacement is completed. After the temporary array is converted to a String, 44 */45 public static string replaceSpace (char [] String) is returned) {46 if (string = null) 47 return null; 48 int originalLength = string. length; 49 int spaceCount = 0; 50 for (int I = 0; I <originalLength; I ++) {51 if (string [I] = '') 52 spaceCount ++; 53} 54 int newLength = originalLength + 2 * spaceCount; 55 char [] temp = new char [newLength]; 56 int I = originalLength-1; 57 int j = newLength-1; 58 while (I> = 0) {59 if (string [I] = '') {60 temp [j] = '0 '; 61 temp [J-1] = '2'; 62 temp [J-2] = '%'; 63 j = J-3; 64} else {65 temp [j] = string [I]; 66 j = J-1; 67} 68 I = I-1; 69} 70 return new String (temp); 71} 72 73/* 74 * time complexity for O (n ), use StringBuffer to implement 75 * using the indexOf (String str, int fromIndex) method and subSequence (int start, int end) method to implement 76 */77 public static String replaceSpace (StringBuffer str) {78 if (str = null) 79 return null; 80 int fromIndex = 0; 81 int index = 0; 82 StringBuffer temp = new StringBuffer (); 83 while (index <= str. length () {84 index = str. indexOf ("", fromIndex); 85 if (index> = 0) {86 temp. append (str. subSequence (fromIndex, index )). append ("% 20"); 87 index = index + 1; 88 fromIndex = index; 89} else {90 temp. append (str. substring (fromIndex, str. length (); 91 break; 92} 93} 94 return temp. toString (); 95} 96 97}