Maximum 69 number (examplehub#77)

realDuYuanChao · github-actions · web-flow · commit 024a9933ba6f · 2021-03-20T21:42:50.000+08:00
* maximum-69-number

* Formatted with Google Java Formatter

Co-authored-by: github-actions &lt;${GITHUB_ACTOR}@users.noreply.github.com&gt;
diff --git a/src/main/java/com/examplehub/leetcode/easy/Maximum69Number.java b/src/main/java/com/examplehub/leetcode/easy/Maximum69Number.java
@@ -0,0 +1,19 @@
+package com.examplehub.leetcode.easy;
+
+/** https://leetcode.com/problems/maximum-69-number/ */
+public class Maximum69Number {
+  public static int solution1(int num) {
+    StringBuilder builder = new StringBuilder(num + "");
+    int maxNumber = num;
+    for (int i = 0; i < builder.length(); ++i) {
+      StringBuilder copyBuilder = new StringBuilder(builder);
+      builder.setCharAt(i, '9');
+      int newNumber = Integer.parseInt(builder.toString());
+      if (newNumber > maxNumber) {
+        maxNumber = newNumber;
+      }
+      builder = copyBuilder;
+    }
+    return maxNumber;
+  }
+}
diff --git a/src/test/java/com/examplehub/leetcode/easy/Maximum69NumberTest.java b/src/test/java/com/examplehub/leetcode/easy/Maximum69NumberTest.java
@@ -0,0 +1,14 @@
+package com.examplehub.leetcode.easy;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+class Maximum69NumberTest {
+  @Test
+  void testSolution1() {
+    assertEquals(Maximum69Number.solution1(9669), 9969);
+    assertEquals(Maximum69Number.solution1(9996), 9999);
+    assertEquals(Maximum69Number.solution1(9999), 9999);
+  }
+}
