solves replace all to avoid consecutive repeating characters

Author: anishLearnsToCode

README.md

@@ -394,3 +394,4 @@
 | 1560 | [Most Visited Sector in a Circular Track](https://leetcode.com/problems/most-visited-sector-in-a-circular-track)                                     |                                                        [![Java](assets/java.png)](src/MostVisitedSectorInACircularTrack.java)                                                        |                                                                                                                                   |
 | 1566 | [Detect Pattern of Length M Repeated K or More Times](https://leetcode.com/problems/detect-pattern-of-length-m-repeated-k-or-more-times)             |                                                   [![Java](assets/java.png)](src/DetectPatternOfLengthMRepeatedKOrMoreTimes.java)                                                    |                                                                                                                                   |
 | 1572 | [Matrix Diagonal Sum](https://leetcode.com/problems/matrix-diagonal-sum)                                                                             |                                                                [![Java](assets/java.png)](src/MatrixDiagonalSum.java)                                                                |                                                                                                                                   |
+| 1576 | [Replace All ?'s to Avoid Consecutive Repeating Characters](https://leetcode.com/problems/replace-all-s-to-avoid-consecutive-repeating-characters)   |                                                 [![Java](assets/java.png)](src/ReplaceAllToAvoidConsecutiveRepeatingCharacters.java)                                                 |                                                                                                                                   |

src/ReplaceAllToAvoidConsecutiveRepeatingCharacters.java

@@ -0,0 +1,30 @@
+// https://leetcode.com/problems/replace-all-s-to-avoid-consecutive-repeating-characters/submissions
+// T:(n)
+// S: O(n)
+
+public class ReplaceAllToAvoidConsecutiveRepeatingCharacters {
+    private static final Character QUESTION_MARK = '?';
+
+    public String modifyString(String s) {
+        final StringBuilder result = new StringBuilder();
+        char last = QUESTION_MARK;
+        for (int index = 0 ; index < s.length() ; index++) {
+            char c = s.charAt(index);
+            if (c == QUESTION_MARK) {
+                char left = get(s, index - 1);
+                if (left == QUESTION_MARK) left = last;
+                final char right = get(s, index + 1);
+                c = 'a';
+                while (c == left || c == right) c++;
+                last = c;
+            }
+            result.append(c);
+        }
+        return result.toString();
+    }
+
+    private char get(String string, int index) {
+        if (index < 0 || index >= string.length()) return QUESTION_MARK;
+        return string.charAt(index);
+    }
+}