Add length of last word problem

Author: sudheerj

README.md

@@ -71,6 +71,7 @@ List of Programs related to data structures and algorithms
 |  9  | Encode and decode strings                      |                   [Source](https://github.com/sudheerj/datastructures-algorithms/blob/master/src/javascript/algorithms/strings/9.encodeDecodeStrings/encodeDecodeStrings.js)                   |                   [JavaScript](https://livecodes.io/?console&x=https://github.com/sudheerj/datastructures-algorithms/blob/master/src/javascript/algorithms/strings/9.encodeDecodeStrings/encodeDecodeStrings.js)                   |                   [Documentation](https://github.com/sudheerj/datastructures-algorithms/blob/master/src/javascript/algorithms/strings/9.encodeDecodeStrings/encodeDecodeStrings.md)                   | Medium | Basic string and array operations |
 | 10  | Greatest common devisor of strings             |                [Source](https://github.com/sudheerj/datastructures-algorithms/blob/master/src/javascript/algorithms/strings/10.greatestCommonDivisor/greatestCommonDivisor.js)                 |                [JavaScript](https://livecodes.io/?console&x=https://github.com/sudheerj/datastructures-algorithms/blob/master/src/javascript/algorithms/strings/10.greatestCommonDivisor/greatestCommonDivisor.js)                 |                [Documentation](https://github.com/sudheerj/datastructures-algorithms/blob/master/src/javascript/algorithms/strings/10.greatestCommonDivisor/greatestCommonDivisor.md)                 |  Easy  |  Euclidean and String operations  |
 | 11  | Reverse words in string                        |                 [Source](https://github.com/sudheerj/datastructures-algorithms/blob/master/src/javascript/algorithms/strings/11.reverseWordsInString/reverseWordsInString.js)                  |                 [JavaScript](https://livecodes.io/?console&x=https://github.com/sudheerj/datastructures-algorithms/blob/master/src/javascript/algorithms/strings/11.reverseWordsInString/reverseWordsInString.js)                  |                 [Documentation](https://github.com/sudheerj/datastructures-algorithms/blob/master/src/javascript/algorithms/strings/11.reverseWordsInString/reverseWordsInString.md)                  | Medium | Basic string and array operations |
+| 12  | Length of last word                      |                 [Source](https://github.com/sudheerj/datastructures-algorithms/blob/master/src/javascript/algorithms/strings/12.lastWordLength/lastWordLength.js)                  |                 [JavaScript](https://livecodes.io/?console&x=https://github.com/sudheerj/datastructures-algorithms/blob/master/src/javascript/algorithms/strings/12.lastWordLength/lastWordLength.js)                  |                 [Documentation](https://github.com/sudheerj/datastructures-algorithms/blob/master/src/javascript/algorithms/strings/12.lastWordLength/lastWordLength.md)                  | Easy | String traversal |
 
 ### Dynamic programming
 

src/java1/algorithms/strings/lastWordLength/LastWordLength.java

@@ -0,0 +1,25 @@
+package java1.algorithms.strings.lastWordLength;
+
+public class LastWordLength {
+    private static int lengthOfLastWord(String str){
+        int i = str.length()-1, length = 0;
+
+        while(str.charAt(i) == ' '){
+            i--;
+        }
+
+        while (i >= 0 && str.charAt(i) != ' ') {
+            i--;
+            length++;
+        }
+
+        return length;
+    }
+    public static void main(String[] args) {
+        String str1 = "Welcome to DSA";
+        String str2 = " My pet is fluffy  ";
+
+        System.out.println(lengthOfLastWord(str1));
+        System.out.println(lengthOfLastWord(str2));
+    }
+}

src/java1/algorithms/strings/lastWordLength/LastWordLength.md

@@ -0,0 +1,29 @@
+**Description:**
+Given an input string `str` which consists of words and spaces, Return the length of last word in the string.
+
+**Note:** The word is considered as a maximal substring with non-space characters.
+
+### Examples
+Example 1:
+Input: "Welcome to DSA"
+Output: 3
+
+Example 2:
+Input: " My pet is fluffy  "
+Output: 6
+
+**Algorithmic Steps**
+This problem is solved with the help of string traversal. The algorithmic approach can be summarized as follows:
+
+1. Define the last index(i.e,`i`) of the given string and initialize length of last word(i.e, `length`) to 0.
+
+2. Trim the ending spaces to find the last non-space character's index. This can be done through iteration from the end of a string.
+   
+3. Find the length of last word by iterating the string until the space character is found.
+
+4. Return length of last word as an output.
+
+**Time and Space complexity:**
+This algorithm has a time complexity of `O(n)` where `n` is the length of given string. This is because we may need to iterate entire string incase of single word string(worst case scenario).
+
+Also, it takes constant( `O(1)`) space complexity because of no additional variables required other than length output variable.

src/javascript/algorithms/strings/12.lastWordLength/lastWordLength.js

@@ -0,0 +1,20 @@
+function lengthOfLastWord(str){
+    let i = str.length-1, length = 0;
+
+    while(str[i] === ' '){
+        i--;
+    }
+
+    while(i >=0 && str[i] !== ' '){
+        length++;
+        i--;
+    }
+
+    return length;
+}
+
+let str1 = "Welcome to DSA";
+let str2 = " My pet is fluffy  ";
+
+console.log(lengthOfLastWord(str1));
+console.log(lengthOfLastWord(str2));

src/javascript/algorithms/strings/12.lastWordLength/lastWordLength.md

@@ -0,0 +1,29 @@
+**Description:**
+Given an input string `str` which consists of words and spaces, Return the length of last word in the string.
+
+**Note:** The word is considered as a maximal substring with non-space characters.
+
+### Examples
+Example 1:
+Input: "Welcome to DSA"
+Output: 3
+
+Example 2:
+Input: " My pet is fluffy  "
+Output: 6
+
+**Algorithmic Steps**
+This problem is solved with the help of string traversal. The algorithmic approach can be summarized as follows:
+
+1. Define the last index(i.e,`i`) of the given string and initialize length of last word(i.e, `length`) to 0.
+
+2. Trim the ending spaces to find the last non-space character's index. This can be done through iteration from the end of a string.
+   
+3. Find the length of last word by iterating the string until the space character is found.
+
+4. Return length of last word as an output.
+
+**Time and Space complexity:**
+This algorithm has a time complexity of `O(n)` where `n` is the length of given string. This is because we may need to iterate entire string incase of single word string(worst case scenario).
+
+Also, it takes constant( `O(1)`) space complexity because of no additional variables required other than length output variable.