solves #2566: Maximum Difference by Remapping a Digit in java

Author: anishLearnsToCode

Diff for: README.md

@@ -801,7 +801,7 @@
 | 2553 | [Separate the Digits in an Array](https://leetcode.com/problems/separate-the-digits-in-an-array)                                                                       |                                                                                 [![Java](assets/java.png)](src/SeparateTheDigitsInAnArray.java)                                                                                  |                                                                                                                                   |
 | 2558 | [Take Gifts From the Richest Pile](https://leetcode.com/problems/take-gifts-from-the-richest-pile)                                                                     |                                                                                 [![Java](assets/java.png)](src/TakeGiftsFromTheRichestPile.java)                                                                                 |                                                                                                                                   |
 | 2562 | [Find the Array Concatenation Value](https://leetcode.com/problems/find-the-array-concatenation-value)                                                                 |                                                                               [![Java](assets/java.png)](src/FindTheArrayConcatenationValue.java)                                                                                |                                                                                                                                   |
-| 2566 | [Maximum Difference by Remapping a Digit](https://leetcode.com/problems/maximum-difference-by-remapping-a-digit)                                                       |                                                                                                                                                                                                                                  |                                                                                                                                   |
+| 2566 | [Maximum Difference by Remapping a Digit](https://leetcode.com/problems/maximum-difference-by-remapping-a-digit)                                                       |                                                                             [![Java](assets/java.png)](src/MaximumDifferenceByRemappingADigit.java)                                                                              |                                                                                                                                   |
 | 2570 | [Merge Two 2D Arrays by Summing Values](https://leetcode.com/problems/merge-two-2d-arrays-by-summing-values)                                                           |                                                                                                                                                                                                                                  |                                                                                                                                   |
 | 2574 | [Left and Right Sum Differences](https://leetcode.com/problems/left-and-right-sum-differences)                                                                         |                                                                                                                                                                                                                                  |                                                                                                                                   |
 | 2578 | [Split With Minimum Sum](https://leetcode.com/problems/split-with-minimum-sum)                                                                                         |                                                                                                                                                                                                                                  |                                                                                                                                   |

Diff for: src/MaximumDifferenceByRemappingADigit.java

@@ -0,0 +1,37 @@
+// https://leetcode.com/problems/maximum-difference-by-remapping-a-digit
+// T: O(log(N))
+// S: O(1)
+
+public class MaximumDifferenceByRemappingADigit {
+    public int minMaxDifference(int num) {
+        final String number = num + "";
+        final int maxDigit = maxDigit(number);
+        final int minDigit = minDigit(number);
+        return maxDigit - minDigit;
+    }
+
+    private int maxDigit(String x) {
+        for (int i = 0 ; i < x.length() ; i++) {
+            int digit = x.charAt(i) - '0';
+            if (digit < 9) {
+                return changeOccurrence(x, digit, 9);
+            }
+        }
+        return Integer.parseInt(x);
+    }
+
+    private int minDigit(String x) {
+        for (int i = 0 ; i < x.length() ; i++) {
+            int digit = x.charAt(i) - '0';
+            if (digit != 0) {
+                return changeOccurrence(x, digit, 0);
+            }
+        }
+        return Integer.parseInt(x);
+    }
+
+    private int changeOccurrence(String x, int digit, int to) {
+        final String result = x.replace((char) (digit + '0'), (char) (to + '0'));
+        return Integer.parseInt(result);
+    }
+}