solves largest substring between two equal characters

Author: anishLearnsToCode

README.md

@@ -1,7 +1,7 @@
 # LeetCode Algorithms
 
-![problems-solved](https://img.shields.io/badge/Problems%20Solved-326/2081-1f425f.svg)
-![problems-solved-java](https://img.shields.io/badge/Java-326/2081-1abc9c.svg)
+![problems-solved](https://img.shields.io/badge/Problems%20Solved-328/2081-1f425f.svg)
+![problems-solved-java](https://img.shields.io/badge/Java-328/2081-1abc9c.svg)
 ![problems-solved-python](https://img.shields.io/badge/Python-186/2081-1abc9c.svg)
 [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](CONTRIBUTING.md)
 [![cp](https://img.shields.io/badge/also%20see-Competitve%20Programming-1f72ff.svg)](https://github.com/anishLearnsToCode/competitive-programming)
@@ -403,7 +403,7 @@
 | 1608 | [Special Array With X Elements Greater Than or Equal X](https://leetcode.com/problems/special-array-with-x-elements-greater-than-or-equal-x)              |                                                  [![Java](assets/java.png)](src/SpecialArrayWithXElementsGreaterThanEqualToX.java)                                                   |                                                                                                                                   |
 | 1614 | [Maximum Nesting Depth of the Parentheses](https://leetcode.com/problems/maximum-nesting-depth-of-the-parentheses)                                        |                                                       [![Java](assets/java.png)](src/MaximumNestingDepthOfTheParentheses.java)                                                       |                                                                                                                                   |
 | 1619 | [Mean of Array After Removing Some Elements](https://leetcode.com/problems/mean-of-array-after-removing-some-elements)                                    |                                                      [![Java](assets/java.png)](src/MeanOfArrayAfterRemovingSomeElements.java)                                                       |                                                                                                                                   |
-| 1624 | [Largest Substring Between Two Equal Characters](https://leetcode.com/problems/largest-substring-between-two-equal-characters)                            |                                                                                                                                                                                      |                                                                                                                                   |
+| 1624 | [Largest Substring Between Two Equal Characters](https://leetcode.com/problems/largest-substring-between-two-equal-characters)                            |                                                    [![Java](assets/java.png)](src/LargestSubStringBetweenTwoEqualCharacters.java)                                                    |                                                                                                                                   |
 | 1629 | [Slowest Key](https://leetcode.com/problems/slowest-key)                                                                                                  |                                                                                                                                                                                      |                                                                                                                                   |
 | 1636 | [Sort Array by Increasing Frequency](https://leetcode.com/problems/sort-array-by-increasing-frequency)                                                    |                                                                                                                                                                                      |                                                                                                                                   |
 | 1640 | [Check Array Formation Through Concatenation](https://leetcode.com/problems/check-array-formation-through-concatenation)                                  |                                                                                                                                                                                      |                                                                                                                                   |

src/LargestSubStringBetweenTwoEqualCharacters.java

@@ -0,0 +1,17 @@
+import java.util.HashMap;
+import java.util.Map;
+
+public class LargestSubStringBetweenTwoEqualCharacters {
+    public int maxLengthBetweenEqualCharacters(String s) {
+        int maxLength = -1;
+        final Map<Character, Integer> lastIndex = new HashMap<>();
+        for (int i = 0 ; i < s.length() ; i++) {
+            if (lastIndex.containsKey(s.charAt(i))) {
+                maxLength = Math.max(maxLength, i - lastIndex.get(s.charAt(i)) - 1);
+            } else {
+                lastIndex.put(s.charAt(i), i);
+            }
+        }
+        return maxLength;
+    }
+}