calcuate middle index (#110)

realDuYuanChao · web-flow · commit 5d0a480a71b8 · 2021-04-21T09:50:36.000+08:00
diff --git a/src/main/java/com/examplehub/searches/BinarySearch.java b/src/main/java/com/examplehub/searches/BinarySearch.java
@@ -1,5 +1,7 @@
 package com.examplehub.searches;
 
+import com.examplehub.maths.MiddleIndexCalculate;
+
 public class BinarySearch implements Search {
 
   /**
@@ -14,7 +16,7 @@ public int search(int[] numbers, int key) {
     int left = 0;
     int right = numbers.length - 1;
     while (left <= right) {
-      int mid = left + (right - left) / 2;
+      int mid = MiddleIndexCalculate.middle(left, right);
       if (key == numbers[mid]) {
         return mid;
       } else if (key > numbers[mid]) {
diff --git a/src/main/java/com/examplehub/searches/BinarySearchRecursion.java b/src/main/java/com/examplehub/searches/BinarySearchRecursion.java
@@ -1,5 +1,7 @@
 package com.examplehub.searches;
 
+import com.examplehub.maths.MiddleIndexCalculate;
+
 public class BinarySearchRecursion implements Search {
 
   @Override
@@ -20,7 +22,7 @@ public int search(int[] numbers, int left, int right, int key) {
     if (left > right) {
       return -1;
     }
-    int mid = left + (right - left) / 2;
+    int mid = MiddleIndexCalculate.middle(left, right);
     if (key == numbers[mid]) {
       return mid;
     } else if (key >= numbers[mid]) {
@@ -49,7 +51,7 @@ public <T extends Comparable<T>> int search(T[] array, int left, int right, T ke
     if (left > right) {
       return -1;
     }
-    int mid = left + (right - left) / 2;
+    int mid = MiddleIndexCalculate.middle(left, right);
     if (key.compareTo(array[mid]) == 0) {
       return mid;
     } else if (key.compareTo(array[mid]) > 0) {
diff --git a/src/main/java/com/examplehub/sorts/MergeSort.java b/src/main/java/com/examplehub/sorts/MergeSort.java
@@ -1,5 +1,7 @@
 package com.examplehub.sorts;
 
+import com.examplehub.maths.MiddleIndexCalculate;
+
 public class MergeSort implements Sort {
 
   @Override
@@ -21,7 +23,7 @@ public <T extends Comparable<T>> void sort(T[] array) {
    */
   public static void mergeSort(int[] numbers, int left, int right) {
     if (left < right) {
-      int middle = (left + right) >> 1;
+      int middle = MiddleIndexCalculate.middle(left, right);
       mergeSort(numbers, left, middle);
       mergeSort(numbers, middle + 1, right);
       merge(numbers, left, right);
