Suppose we have given a string in which some ranges as specified and we have to place the numbers which is between the given range in the specified place as provided and depicted in the illustration below as follows for a better understanding.
Illustration:
Input : string x = "1-5, 8, 11-14, 18, 20, 26-29"
Output : string y = "1, 2, 3, 4, 5, 8, 11, 12,
13, 14, 18, 20, 26, 27, 28, 29"
Approach:
In order to solve the above problem, we can follow the below approach:
- First, we have to split the String into String[] array. We have to split the String where we found – symbol.
- Now we have a String[] array with the elements. Now we just go to the first index last element i.e. 1 and the preceding index first element of the String[] array say it be 5.
- After that with the help of for loop, we can add the numbers which are between 1 and 5 and store them in the String variable.
- The above process continues till the length of the string array.
Note:
With the help of Collections and various utility methods we can solve the problem easily but the Collections concept is not a good option performance-wise. If we go through Collections, performance is reduced and time complexity is also increased. There in the below program we explicitly define our own split method and logic.
Implementation: Here we will now be proposing and discussing all three scenarios with help of a clean java program as follows:
Example 1:
Java
// Java program to Expand a String if Range is Given// Main classpublic class Solution { // Main driver method public static void expand(String word) { // Creating an object of StringBuffer class to // make a modifiable string object StringBuilder sb = new StringBuilder(); // Get all intervals String[] strArr = word.split(", "); // Traverse through every interval for (int i = 0; i < strArr.length; i++) { // Get lower and upper String[] a = strArr[i].split("-"); // Setting high and low counters if (a.length == 2) { int low = Integer.parseInt(a[0]); int high = Integer.parseInt(a[a.length - 1]); // Condition check holds true // Till low counter is lesser or equal to // high counter while (low <= high) { // Append all numbers sb.append(low + " "); low++; } } // If we reaches here then // High counter exceeds lower counter else { sb.append(strArr[i] + " "); } } // Print the modifiable string System.out.println(sb.toString()); } // Method 2 // Main driver method public static void main(String args[]) { // Custom input string as input String s = "1-5, 8, 11-14, 18, 20, 26-29"; expand(s); }} |
Output:
1 2 3 4 5 8 11 12 13 14 18 20 26 27 28 29
Example 2:
Java
// Java Program to Illustrate Expansion of String// Main classpublic class StringExpand { // Method 1 // To split the string static String[] split(String st) { // Count how many words in our string // Irrespective of spaces int wc = countWords(st); String w[] = new String[wc]; char[] c = st.toCharArray(); int k = 0; for (int i = 0; i < c.length; i++) { // Initially declaring and initializing // string as empty String s = ""; // Whenever we found an non-space character while (i < c.length && c[i] != ' ') { // Concat with the String s // Increment the value of i s = s + c[i]; i++; } // If the String is not empty if (s.length() != 0) { // Add the String to the String[] // array w[k] = s; k++; } } // Returning the string array return w; } // Method 2 // To count the number of words in a string static int countWords(String str) { int count = 0; for (int i = 0; i < str.length(); i++) { // The below condition to check // whether the first character is // space or not if (i == 0 && str.charAt(i) != ' ' || str.charAt(i) != ' ' && str.charAt(i - 1) == ' ') { count++; } } // Returning the count return count; } // Method 3 // To expand the string public static void expand(String s) { String p = s; String[] arr = p.split("\\-"); String k = ""; // Traversing over array using for loop for (int i = 0; i < arr.length; i++) { // Case 1 if (i != arr.length - 1) { String[] arr1 = arr[i].split(", "); String[] arr2 = arr[i + 1].split(", "); int a = Integer.parseInt( arr1[arr1.length - 1]); int b = Integer.parseInt(arr2[0]); for (int j = a + 1; j < b; j++) { arr[i] = arr[i] + ", " + j; } } // Case 2 if (k != "") k = k + ", " + arr[i]; // Case 3 else k = k + arr[i]; } // Print the expanded string System.out.println(k); } // Method 4 // Main driver method public static void main(String[] args) { // Custom string input String s = "1-5, 8, 11-14, 18, 20, 26-29"; // Calling the method 3 to // expand the string expand(s); }} |
Output:
1, 2, 3, 4, 5, 8, 11, 12, 13, 14, 18, 20, 26, 27, 28, 29
Example 3:
Java
// Java program to Expand a String if Range is Given// Main class// GenerateStringOnRangeclass GFG { // Method 1 // To generate string on range public static String generateStringOn(String input) { String[] words = input.split(" "); // Initially setting up range String[] ranges = null; int number = 0; // Creating a StringBuffer object so that // we can modify the string StringBuffer buffer = new StringBuffer(); // Looking out for words by // iterating using for each loop for (String word : words) { // To be replaced by // using replace() method word = word.replace(",", ""); // If word is containing "-" character if (word.contains("-")) { ranges = word.split("-"); number = Integer.parseInt(ranges[0]); // Till number is within range while (number <= Integer.parseInt(ranges[1])) { // Append , in between them buffer.append(number + ", "); number++; } } // If we reaches here then // word does contains "-" else { buffer.append(word + ", "); } } // Return the StringBuffer object return buffer.toString(); } // Method 2 // Main driver method public static void main(String[] args) { // Custom input string String input = "1-5, 8, 11-14, 18, 20, 26-29"; // Calling the method 1 as created above System.out.println(generateStringOn(input)); }} |
Output
1, 2, 3, 4, 5, 8, 11, 12, 13, 14, 18, 20, 26, 27, 28, 29,
