Fixed SonarQube warnings

src/main/java/g0001_0100/s0008_string_to_integer_atoi/Solution.java

@@ -4,7 +4,7 @@
 
 public class Solution {
     public int myAtoi(String str) {
-        if (str == null || str.length() == 0) {
+        if (str == null || str.isEmpty()) {
             return 0;
         }
         int i = 0;

src/main/java/g0001_0100/s0014_longest_common_prefix/Solution.java

@@ -14,7 +14,7 @@ public String longestCommonPrefix(String[] strs) {
         String temp = strs[0];
         int i = 1;
         String cur;
-        while (temp.length() > 0 && i < strs.length) {
+        while (!temp.isEmpty() && i < strs.length) {
             if (temp.length() > strs[i].length()) {
                 temp = temp.substring(0, strs[i].length());
             }

src/main/java/g0001_0100/s0065_valid_number/Solution.java

@@ -4,7 +4,7 @@
 
 public class Solution {
     public boolean isNumber(String s) {
-        if (s == null || s.length() == 0) {
+        if (s == null || s.isEmpty()) {
             return false;
         }
         boolean eSeen = false;

src/main/java/g0201_0300/s0282_expression_add_operators/Solution.java

@@ -9,7 +9,7 @@
 public class Solution {
     public List<String> addOperators(String num, int target) {
         List<String> res = new ArrayList<>();
-        if (num.length() == 0 || Long.parseLong(num) > Integer.MAX_VALUE) {
+        if (num.isEmpty() || Long.parseLong(num) > Integer.MAX_VALUE) {
             return res;
         }
         char[] list = num.toCharArray();

src/main/java/g0401_0500/s0434_number_of_segments_in_a_string/Solution.java

@@ -5,13 +5,13 @@
 public class Solution {
     public int countSegments(String s) {
         s = s.trim();
-        if (s.length() == 0) {
+        if (s.isEmpty()) {
             return 0;
         }
         String[] splitted = s.split(" ");
         int result = 0;
         for (String value : splitted) {
-            if (value.length() > 0) {
+            if (!value.isEmpty()) {
                 result++;
             }
         }

src/main/java/g0401_0500/s0468_validate_ip_address/Solution.java

@@ -6,7 +6,7 @@ public class Solution {
     private static final String NEITHER = "Neither";
 
     public String validIPAddress(String ip) {
-        if (ip.length() == 0) {
+        if (ip.isEmpty()) {
             return NEITHER;
         }
         String[] arr = ip.split("\\.", -1);
@@ -24,7 +24,7 @@ public String validIPAddress(String ip) {
             return "IPv4";
         } else if (arr1.length == 8) {
             for (String num : arr1) {
-                if (num.length() < 1 || num.length() > 4) {
+                if (num.isEmpty() || num.length() > 4) {
                     return NEITHER;
                 }
                 for (int j = 0; j < num.length(); j++) {

src/main/java/g0401_0500/s0488_zuma_game/Solution.java

@@ -16,10 +16,10 @@ private int dfs(String board, String hand) {
     }
 
     private int findMinStepDp(String board, String hand, Map<String, Map<String, Integer>> dp) {
-        if (board.length() == 0) {
+        if (board.isEmpty()) {
             return 0;
         }
-        if (hand.length() == 0) {
+        if (hand.isEmpty()) {
             return -1;
         }
         if (dp.get(board) != null && dp.get(board).get(hand) != null) {

src/main/java/g0501_0600/s0520_detect_capital/Solution.java

@@ -4,7 +4,7 @@
 
 public class Solution {
     public boolean detectCapitalUse(String word) {
-        if (word == null || word.length() == 0) {
+        if (word == null || word.isEmpty()) {
             return false;
         }
         int upper = 0;

src/main/java/g0601_0700/s0664_strange_printer/Solution.java

@@ -4,7 +4,7 @@
 
 public class Solution {
     public int strangePrinter(String s) {
-        if (s.length() == 0) {
+        if (s.isEmpty()) {
             return 0;
         }
         int[][] dp = new int[s.length()][s.length()];

src/main/java/g0701_0800/s0761_special_binary_string/Solution.java

@@ -6,7 +6,7 @@
 
 public class Solution {
     public String makeLargestSpecial(String s) {
-        if (s == null || s.length() == 0 || s.length() == 2) {
+        if (s == null || s.isEmpty() || s.length() == 2) {
             return s;
         }
         PriorityQueue<String> pq = new PriorityQueue<>((a, b) -> b.compareTo(a));
@@ -32,7 +32,7 @@ public String makeLargestSpecial(String s) {
         while (!pq.isEmpty()) {
             ans.append(pq.poll());
         }
-        if (ans.length() == 0) {
+        if (ans.isEmpty()) {
             ans.append('1');
             ans.append(makeLargestSpecial(s.substring(1, s.length() - 1)));
             ans.append('0');

src/main/java/g1001_1100/s1002_find_common_characters/Solution.java

@@ -26,7 +26,7 @@ public List<String> commonChars(String[] words) {
     }
 
     private String getCommon(String s1, String s2) {
-        if (s1.length() == 0 || s2.length() == 0) {
+        if (s1.isEmpty() || s2.isEmpty()) {
             return "";
         }
         int[] c1c = countChars(s1);

src/main/java/g1101_1200/s1138_alphabet_board_path/Solution.java

@@ -4,7 +4,7 @@
 
 public class Solution {
     public String alphabetBoardPath(String target) {
-        if (target.length() == 0) {
+        if (target.isEmpty()) {
             return "";
         }
         int sourceRow = 0;

src/main/java/g1701_1800/s1704_determine_if_string_halves_are_alike/Solution.java

@@ -4,7 +4,7 @@
 
 public class Solution {
     public boolean halvesAreAlike(String s) {
-        if (s.length() < 1) {
+        if (s.isEmpty()) {
             return false;
         }
         return countVowel(0, s.length() / 2, s) == countVowel(s.length() / 2, s.length(), s);

src/main/java/g1801_1900/s1898_maximum_number_of_removable_characters/Solution.java

@@ -5,7 +5,7 @@
 
 public class Solution {
     public int maximumRemovals(String s, String p, int[] removable) {
-        if (s == null || s.length() == 0) {
+        if (s == null || s.isEmpty()) {
             return 0;
         }
         // binary search for the k which need to be removed

src/main/java/g1901_2000/s1948_delete_duplicate_folders_in_system/Solution.java

@@ -66,14 +66,14 @@ private void calculateHash() {
                 folder.calculateHash();
                 builder.append('#');
                 builder.append(foldername);
-                if (folder.folderHash.length() > 0) {
+                if (!folder.folderHash.isEmpty()) {
                     builder.append('(');
                     builder.append(folder.folderHash);
                     builder.append(')');
                 }
             }
             folderHash = builder.toString();
-            if (folderHash.length() > 0) {
+            if (!folderHash.isEmpty()) {
                 ArrayList<Folder> duplicateFolders =
                         duplicates.computeIfAbsent(folderHash, k -> new ArrayList<>());
                 duplicateFolders.add(this);